Optical film

ABSTRACT

The present invention provides a method for producing an optical film excellent in anti-fouling properties and scratch resistance as well as anti-reflection properties. The method includes the steps of: (1) applying a lower layer resin and an upper layer resin; (2) forming a resin layer having the uneven structure on a surface thereof by pressing a mold against the lower layer resin and the upper layer resin from the upper layer resin side in the state where the applied lower layer resin and upper layer resin are stacked; and (3) curing the resin layer, the lower layer resin containing at least one kind of first monomer that contains no fluorine atoms, the upper layer resin containing a fluorine-containing monomer and at least one kind of second monomer that contains no fluorine atoms, at least one of the first monomer and the second monomer containing a compatible monomer that is compatible with the fluorine-containing monomer and being dissolved in the lower layer resin and the upper layer resin.

PRIORITY STATEMENT

This application is a divisional application of and claims priorityunder 35 U.S.C. §§ 120,121 to U.S. application Ser. No. 15/649,755 filedJul. 14, 2017, which is a divisional application of and claims priorityunder 35 U.S.C. §§ 120,121 to U.S. application Ser. No. 15/118,536 filedAug. 12, 2016, which is a national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/JP2016/053985 which has anInternational filing date of Feb. 10, 2016, and claims priority under 35U.S.C. § 119 to Japanese Patent Application No. 2015092967, filed onApr. 30, 2015, and Japanese Patent Application No. 2015226792, filed onNov. 19, 2015, the entire contents of each of which are herebyincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to methods for producing an optical film,and optical films. More specifically, the present invention relates to amethod for producing an optical film having a nanometer-sized unevenstructure, and to an optical film produced by the method for producingan optical film.

BACKGROUND ART

Optical films having a nanometer-sized uneven structure (nanostructure)are known to be used as anti-reflection films. Such an uneven structurehas a refractive index continuously changing from the air layer to thebase film, which enables significant reduction of the reflected light.Those optical films have excellent anti-reflection properties, but havea disadvantage that due to the uneven structure of their surfaces, dirtsuch as a fingerprint (sebum) easily spreads once it has adhered to thesurface, and it may be difficult to wipe off the dirt that has enteredthe gaps between the projections. Also, since the adhered dirt has areflectance greatly different from the optical film, the dirt can beeasily recognized. For these reasons, water- and oil-repellent opticalfilms having excellent anti-fouling properties have been desired. PatentLiteratures 1 to 3, for example, disclose configurations responding tothe desire, such as a configuration in which a layer made of afluorine-based material is formed on the surface having the unevenstructure, and a configuration in which a fluorine-based material isadded to the uneven structure.

CITATION LIST Patent Literature

-   Patent Literature 1: JP 2003-172808 A-   Patent Literature 2: JP 2007-178724 A-   Patent Literature 3: JP 2014-153524 A-   Patent Literature 4: WO 2011/013615

Non Patent Literature

-   Non Patent Literature 1: R. F. Fedors, Polym. Eng. Sci., 14[2],    1974, pp. 147-154-   Non Patent Literature 2: J. Brandrup et al., “Solubility Parameter    Values”, Polymer Handbook, 4th edition-   Non Patent Literature 3: K. Milam et al., “Optool™ DAC-HP: An    Anti-fingerprint Coating Material for Touch Panel Screens”, SID11    DIGEST, 2011, pp. 1826-1829 Non Patent Literature 4: Nano Science    Corporation, “Useful tips for XPS analysis (XPS Bunseki no    mame-chishiki”, “Chemical state of carbon (C1s binding energy shift    (chemical shift)) (Kabon no kagaku-jotai (C1s no Ketsugo enerugi no    shifuto (kagaku shifuto))”, [online], 2014, [searched on Nov. 6,    2015], Internet (URL:    http://www.nanoscience.co.jp/knowledge/XPS/knowledge02.html)-   Non Patent Literature 5: A. M. Ferraria et al., “XPS studies of    directly fluorinated HDPE: problems and solutions”, Polymer 44,    2003, pp. 7241-7249-   Non Patent Literature 6: Thermo Fisher Scientific Inc., “Oxygen”,    “Binding energies of common chemical states)”, [online], 2013,    [searched on Nov. 6, 2015], Internet (URL:    http://xpssimplified.com/elements/oxygen.php)-   Non Patent Literature 7: N. Stobie et al., “Silver Doped    Perfluoropolyether-Urethane Coatings: Antibacterial Activity and    Surface Analysis”, Colloids and Surfaces B: Biointerfaces, Vol. 72,    2009, pp. 62-67

SUMMARY OF INVENTION Technical Problem

Conventional optical films, however, have insufficient anti-foulingproperties, and thus can be improved. Also, the fluorine-based material,used to improve the anti-fouling properties, tends to be removed whendirt or the like substance adhering to the surface is wiped off. Hence,those conventional optical films can be improved also from the viewpointof improving the scratch resistance.

Patent Literature 1 discloses a configuration in which a water-repellentfilm made of polytetrafluoroethylene is formed on the surface having anuneven structure. The invention described in Patent Literature 1,however, has low adhesion between the uneven structure and the film madeof polytetrafluoroethylene, and is likely to cause peeling of the film.Besides, since the film made of polytetrafluoroethylene is thin, thestrength of the film is weak, and thus the concentration ofpolytetrafluoroethylene tends to be decreased by a wipe. Thus, thisinvention can still be improved from the viewpoint of improving thescratch resistance.

Patent Literature 2 discloses a method of forming an uneven structureby, between a base film and a mold, supplying a photocurable resincomposition containing a fluorine compound, rolling the composition, andcuring the composition. The invention described in Patent Literature 2,however, has an insufficient fluorine compound concentration on thesurface having the uneven structure, and therefore has insufficient oilrepellency. Thus, this invention can still be improved from theviewpoint of improving the anti-fouling properties.

Patent Literature 3 discloses a configuration in which a lubricatinglayer of a fluorine-based lubricant containing perfluoroalkyl polyethercarboxylic acid is formed on the surface having an uneven structure.However, the invention described in Patent Literature 3 has low adhesionbetween the uneven structure and the lubricating layer of afluorine-based lubricant, and is likely to cause peeling of the layer.Thus, this invention can still be improved from the viewpoint ofimproving the scratch resistance.

The present invention was made in view of the above current state of theart, and aims to provide a method for producing an optical filmexcellent in anti-fouling properties and scratch resistance as well asanti-reflection properties; and an optical film excellent inanti-fouling properties and scratch resistance as well asanti-reflection properties.

Solution to Problem

The inventors have made various studies on methods for producing opticalfilms excellent in anti-fouling properties and scratch resistance aswell as anti-reflection properties. As a result, the inventors havefocused on a method of applying a lower layer resin and an upper layerresin, pressing a mold against the two layers in the stacked state,forming a resin layer having a nanometer-sized uneven structure on thesurface, and curing the resin layer. The inventors have then found thatwhen the monomer component of the upper layer resin contains afluorine-containing monomer and the monomer component of at least one ofthe lower layer resin and the upper layer resin contains a compatiblemonomer being compatible with the fluorine-containing monomer and isdissolved in the lower layer resin and the upper layer resin, theconcentration of fluorine atoms in the vicinity of the surface having anuneven structure is increased, so that the water repellency and oilrepellency are increased. Also, the water repellency and oil repellencyhave been found to be significantly improved and thus excellentanti-fouling properties can be obtained on the surface having ananometer-sized uneven structure, compared with a common surface such asa flat surface. Furthermore, the inventors have found that whencompatible monomers are used, the lower layer resin and the upper layerresin are locally mixed and polymerized in the interface between theresins while the concentration of fluorine atoms in the vicinity of thesurface having the uneven structure is maintained, whereby the resinlayer with an increased adhesion between the resins is formed andexcellent scratch resistance can be obtained. The inventors thereforesolved the above-described problems, and thereby made the presentinvention.

That is, one aspect of the present invention may be a method forproducing an optical film having on a surface thereof an unevenstructure provided with projections at a pitch equal to or shorter thanthe wavelength of visible light, the method including the steps of: (1)applying a lower layer resin and an upper layer resin; (2) forming aresin layer having the uneven structure on a surface thereof by pressinga mold against the lower layer resin and the upper layer resin from theupper layer resin side in the state where the applied lower layer resinand upper layer resin are stacked; and (3) curing the resin layer, thelower layer resin containing at least one kind of first monomer thatcontains no fluorine atoms, the upper layer resin containing afluorine-containing monomer and at least one kind of second monomer thatcontains no fluorine atoms, at least one of the first monomer and thesecond monomer containing a compatible monomer that is compatible withthe fluorine-containing monomer and being dissolved in the lower layerresin and the upper layer resin.

Another aspect of the present invention may be an optical film producedby the above-described method for producing an optical film.

Yet another aspect of the present invention may be an optical filmincluding a cured resin layer having an uneven structure on a surfacethereof, the uneven structure being provided with projections at a pitchequal to or shorter than the wavelength of visible light, the curedresin layer containing carbon atoms, nitrogen atoms, oxygen atoms, andfluorine atoms as constituent atoms, the proportion of the number of thefluorine atoms relative to the total number of the carbon atoms, thenitrogen atoms, the oxygen atoms, and the fluorine atoms on the surfacehaving the uneven structure being 33 atom % or higher, the number of theatoms being measured by X-ray photoelectron spectroscopy under theconditions of an X-ray beam diameter of 100 μm, an analysis area of 1000μm×500 μm, and a photoelectron extraction angle of 45°.

Yet another aspect of the present invention may be an optical filmincluding a cured resin layer having an uneven structure on a surfacethereof, the uneven structure being provided with projections at a pitchequal to or shorter than the wavelength of visible light, the curedresin layer containing carbon atoms, nitrogen atoms, oxygen atoms, andfluorine atoms as constituent atoms, the ratio of a peak area of OCF2bonds to the sum of a peak area of C—O bonds and a peak area of C═Obonds being 0.3 or higher according to spectra obtained by curve-fittingfor the O1s peak on the surface having the uneven structure with a peakattributed to the C—O bonds, a peak attributed to the C═O bonds, and apeak attributed to the OCF2 bonds, the O1s peak being measured by X-rayphotoelectron spectroscopy under the conditions of an X-ray beamdiameter of 100 μm, an analysis area of 1000 μm×500 μm, and aphotoelectron extraction angle of 45°.

Yet another aspect of the present invention may be an optical filmincluding a cured resin layer having an uneven structure on a surfacethereof, the uneven structure being provided with projections at a pitchequal to or shorter than the wavelength of visible light, the curedresin layer containing carbon atoms, nitrogen atoms, oxygen atoms, andfluorine atoms as constituent atoms, D satisfying the equationMFD/MFS=0.3 being 240 nm or more, where MFS, expressed with the unit ofatom %, is the proportion of the number of the fluorine atoms relativeto the total number of the carbon atoms, the nitrogen atoms, the oxygenatoms, and the fluorine atoms on the surface having the unevenstructure, and MFD, expressed with the unit of atom %, is the proportionof the number of the fluorine atoms relative to the total number of thecarbon atoms, the nitrogen atoms, the oxygen atoms, and the fluorineatoms at a position away from the surface having the uneven structure byD, expressed with the unit of nm, in the depth direction in terms ofpolyhydroxy styrene equivalent, the number of the atoms being measuredby X-ray photoelectron spectroscopy under the conditions of an X-raybeam diameter of 100 μm, an analysis area of 1000 μm×500 μm, and aphotoelectron extraction angle of 45°.

Advantageous Effects of Invention

The present invention can provide a method for producing an optical filmexcellent in anti-fouling properties and scratch resistance as well asanti-reflection properties; and an optical film excellent inanti-fouling properties and scratch resistance as well asanti-reflection properties.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates schematic cross-sectional views for explaining theprocess of producing an optical film of Embodiment 1 (steps a to d).

FIG. 2 illustrates schematic cross-sectional views for explaining theprocess of producing an optical film of Embodiment 2 (steps a to c).

FIG. 3 illustrates schematic cross-sectional views for explaining theprocess of producing an optical film of Embodiment 3 (steps a to c).

FIG. 4 illustrates schematic cross-sectional views for explaining theprocess of producing an optical film of Comparative Example 1 (steps ato d).

FIG. 5 illustrates schematic cross-sectional views for explaining theprocess of producing an optical film of Comparative Example 3 (steps ato c).

FIG. 6 is a graph showing the measurement results of the reflectance inExample 7.

FIG. 7 is a graph showing survey spectra of the surfaces of opticalfilms of Study Examples 1 to 4.

FIG. 8 is a graph showing the relation between the thickness of an upperlayer resin and the contact angle.

FIG. 9 is a graph showing the relation between the thickness of an upperlayer resin and the proportion of the number of fluorine atoms relativeto the total number of carbon atoms, nitrogen atoms, oxygen atoms, andfluorine atoms on the surface having an uneven structure.

FIG. 10 includes graphs showing narrow spectra of the surfaces of theoptical films of Study Examples 1 to 4, for (a) C1s peaks, (b) N1speaks, (C) O1s peaks, and (d) F1s peaks.

FIG. 11 is a graph showing an analysis result of the C1s peak in StudyExample 4 shown in the graph (a) of FIG. 10.

FIG. 12 is a graph showing an analysis result of the O1s peak in StudyExample 4 shown in the graph (c) of FIG. 10.

FIG. 13 is a graph showing the relation between the thickness of anupper layer resin and the ratio of the peak area of CF2 bonds to thepeak areas of binding species other than the CF2 bonds in the C1s peak.

FIG. 14 is a graph showing the relation between the thickness of anupper layer resin and the ratio of the peak area of CF3 bonds and OCF2bonds to the peak areas of binding species other than the CF3 bonds andthe OCF2 bonds in the C1s peak.

FIG. 15 is a graph showing the relation between the thickness of anupper layer resin and the ratio of the peak area of OCF2 bonds to thepeak areas of binding species other than the OCF2 bonds in the O1s peak.

FIG. 16 is a graph showing the proportions of the numbers of therespective atoms relative to the total number of carbon atoms, nitrogenatoms, oxygen atoms, and fluorine atoms in a cured resin layer of theoptical film of Study Example 1.

FIG. 17 is a graph showing the proportions of the numbers of therespective atoms relative to the total number of carbon atoms, nitrogenatoms, oxygen atoms, and fluorine atoms in a cured resin layer of theoptical film of Study Example 2.

FIG. 18 is a graph showing the proportions of the numbers of therespective atoms relative to the total number of carbon atoms, nitrogenatoms, oxygen atoms, and fluorine atoms in a cured resin layer of theoptical film of Study Example 3.

FIG. 19 is a graph showing the proportions of the numbers of therespective atoms relative to the total number of carbon atoms, nitrogenatoms, oxygen atoms, and fluorine atoms in a cured resin layer of theoptical film of Study Example 4.

FIG. 20 is a graph showing the distribution states of fluorine atoms inthe cured resin layers of the optical films of Study Examples 1 to 4.

FIG. 21 is a graph showing the distribution states of CF2 bonds in thecured resin layers of the optical films of Study Examples 1 to 4.

FIG. 22 is a graph showing the distribution states of CF3 bonds and OCF2bonds in the cured resin layers of the optical films of Study Examples 1to 4.

FIG. 23 is a graph showing the distribution states of OCF2 bonds in thecured resin layers of the optical films of Study Examples 1 to 4.

FIG. 24 is a graph showing the abundance ratio of carbon atoms of CF2bonds in the cured resin layers of the optical films of Study Examples 1to 4.

FIG. 25 is a graph showing the proportions of the numbers of the atomsof the respective binding species relative to the total number of carbonatoms, nitrogen atoms, oxygen atoms, and fluorine atoms in the curedresin layer of the optical film of Study Example 4.

FIG. 26 is a graph showing M1T and M1ST in Study Example 4 shown in FIG.24.

FIG. 27 is a graph showing the abundance ratio of carbon atoms of CF3bonds and OCF2 bonds in the cured resin layers of the optical films ofStudy Examples 1 to 4.

FIG. 28 is a graph showing M2T and M2ST in Study Example 4 shown in FIG.27.

FIG. 29 is a graph showing the abundance ratio of oxygen atoms of OCF2bonds in the cured resin layers of the optical films of Study Examples 1to 4.

FIG. 30 is a graph showing M3T and M3ST in Study Example 4 shown in FIG.29.

DESCRIPTION OF EMBODIMENTS

The present invention will be described in more detail below withreference to the drawings based on embodiments. The embodiments,however, are not intended to limit the scope of the present invention.Hereinafter, the same portions or the portions having the same functionin different drawings are provided with the same reference numeralexcept for an alphabet following the numeral, and thus the samereference numeral is not repeatedly described. Also, the configurationsof the respective embodiments may suitably be combined or altered withinthe spirit of the present invention.

Embodiment 1

FIG. 1 illustrates schematic cross-sectional views for explaining theprocess of producing an optical film of Embodiment 1 (steps a to d).Hereinafter, the method for producing the optical film of Embodiment 1is described in detail with reference to FIG. 1.

(a) Application of lower layer resin

First, as illustrated in the view (a) of FIG. 1, a lower layer resin 3is applied to a base film 2. Examples of the method for applying thelower layer resin 3 include, but are not particularly limited to,application methods such as the gravure method and the slot die method.

(b) Application of Upper Layer Resin

As illustrated in the view (b) of FIG. 1, an upper layer resin 4 isapplied to the applied lower layer resin 3. As a result, the upper layerresin 4 is formed on the lower layer resin 3 on the side opposite to thebase film 2. Examples of the method for applying the upper layer resin 4include, but are not particularly limited to, application methods suchas the spray method, the gravure method, and the slot die method. Thespray method is preferred because the film thickness is easilyadjustable and the apparatus cost can be suppressed. In particular, itis preferred to perform the application using a swirl nozzle, anelectrostatic nozzle, or an ultrasonic nozzle.

(c) Formation of Uneven Structure

As illustrated in the view (c) of FIG. 1, in the state where the appliedlower layer resin 3 and upper layer resin 4 are stacked, a mold 5 ispressed against the lower layer resin 3 and the upper layer resin 4 fromthe upper layer resin 4 side, so that a resin layer 8 having an unevenstructure on a surface thereof is formed. The resin layer 8 is anintegral form of the lower layer resin 3 and the upper layer resin 4with no interface between these resins. The uneven structure of theresin layer 8 corresponds to a structure in which projections 6 areprovided at a pitch P (distance between the tops of the projections 6adjacent to each other) equal to or shorter than the wavelength ofvisible light, i.e., a moth-eye structure.

(d) Curing of resin layer

The resin layer 8 having the uneven structure is cured. As a result, anoptical film 1 including a cured product of the resin layer 8 having theuneven structure on the surface as illustrated in the view (d) of FIG. 1is completed. Examples of the method for curing the resin layer 8include, but are not particularly limited to, methods utilizing light,heat, or a combination of light and heat. The method is preferably onewhich utilizes ultraviolet rays. The number of times for thephotoirradiation of the resin layer 8 is not particularly limited, andmay be a single time or multiple times. The photoirradiation may beperformed from the base film 2 side or from the resin layer 8 side.

In the production process described above, the steps (a) to (d) can beperformed continuously and efficiently by, for example, using the basefilm 2 with a roll shape.

Each component used in production of the optical film 1 is describedbelow.

Examples of the material of the base film 2 include triacetyl cellulose(TAC) (solubility parameter: 12.2 (cal/cm3)1/2), polyethyleneterephthalate (PET) (solubility parameter: 10.7 (cal/cm3)1/2),polymethyl methacrylate (PMMA) (solubility parameter: 9.06(cal/cm3)1/2), cyclo-olefin polymer (COP) (solubility parameter: 7.4(cal/cm3)1/2), and polycarbonate (PC). The material may be selectedaccording to use environments. Those materials can give high hardness,excellent transparency, and excellent weather resistance to the basefilm 2. The base film 2 may be subjected to an easy adhesion treatment.For example, a TAC film on which an easy adhesion treatment has beenperformed (solubility parameter: 11 (cal/cm3)1/2) may be used. The basefilm 2 may also be subjected to a saponification treatment. For example,a TAC film on which a saponification treatment has been performed(solubility parameter: 16.7 (cal/cm3)1/2) may be used.

The thickness of the base film 2 is not particularly limited, but ispreferably in the range of 10 μm to 120 μm, more preferably in the rangeof 40 μm to 80 μm, from the viewpoint of achieving the transparency andprocessability.

The lower layer resin 3 contains at least one kind of first monomer thatcontains no fluorine atoms. Examples of such a first monomer includeacrylate monomers such as urethane acrylates, polyfunctional acrylates,and monofunctional acrylates, and a mixture of two or more kinds ofacrylate monomers (photocurable resin) may be suitable. Those materialscan give a refractive index suitable in combination use with the basefilm 2, excellent transparency, excellent flexibility, and excellentweather resistance to the lower layer resin 3.

Examples of the urethane acrylates include a urethane acrylate (productname: UA-7100, solubility parameter: 10.2 (cal/cm3)1/2, molecularweight: 1700, surface tension: 85.2 dyn/cm) from Shin-Nakamura ChemicalCo., Ltd., a urethane acrylate (product name: U-4HA, solubilityparameter: 11.3 (cal/cm3)1/2, molecular weight: 600, surface tension:66.6 dyn/cm) from Shin-Nakamura Chemical Co., Ltd., a urethane acrylate(product name: UA-306H, solubility parameter: 10.8 (cal/cm3)1/2,molecular weight: 750, surface tension: 70.0 dyn/cm) from KyoeishaChemical Co., Ltd., and a urethane acrylate (product name: AH-600,solubility parameter: 10.9 (cal/cm3)1/2, molecular weight: 600, surfacetension: 63.1 dyn/cm) from Kyoeisha Chemical Co., Ltd.

Examples of the polyfunctional acrylates include a polyfunctionalacrylate (product name: ATM-35E, solubility parameter: 9.6 (cal/cm3)1/2,molecular weight: 1892, surface tension: 76.8 dyn/cm) from Shin-NakamuraChemical Co., Ltd., a polyfunctional acrylate (product name:A-TMM-3LM-N, solubility parameter: 12.6 (cal/cm3)1/2, molecular weight:298, surface tension: 64.4 dyn/cm) from Shin-Nakamura Chemical Co.,Ltd., a polyfunctional acrylate (product name: TMP-3P, solubilityparameter: 9.4 (cal/cm3)1/2, molecular weight: 470, surface tension:45.2 dyn/cm) from DKS Co. Ltd., a polyfunctional acrylate (product name:BPP-4, solubility parameter: 9.8 (cal/cm3)1/2, molecular weight: 570,surface tension: 51.4 dyn/cm) from DKS Co. Ltd., a polyfunctionalacrylate (product name: PD-070A, solubility parameter: 8.9 (cal/cm3)1/2,molecular weight: 840, surface tension: 51.6 dyn/cm) from Toho ChemicalIndustry Co., Ltd., and a polyfunctional acrylate (product name: 80MFA,solubility parameter: 13.4 (cal/cm3)1/2, molecular weight: 350, surfacetension: 66.6 dyn/cm) from Kyoeisha Chemical Co., Ltd.

Examples of the monofunctional acrylates include an amidegroup-containing monomer (product name: ACMO (registered trademark),solubility parameter: 12.0 (cal/cm3)1/2, molecular weight: 141, surfacetension: 43.7 dyn/cm) from KJ Chemicals Corporation, an amidegroup-containing monomer (product name: HEAA (registered trademark),solubility parameter: 14.4 (cal/cm3)1/2, molecular weight: 115, surfacetension: 45.7 dyn/cm) from KJ Chemicals Corporation, an amidegroup-containing monomer (product name: DEAA (registered trademark),solubility parameter: 10.1 (cal/cm3)1/2, molecular weight: 127, surfacetension: 28.0 dyn/cm) from KJ Chemicals Corporation, a hydroxygroup-containing monomer (product name: CHDMMA, solubility parameter:11.6 (cal/cm3)1/2, molecular weight: 198, surface tension: 43.5 dyn/cm)from Nippon Kasei Chemical Co., Ltd., a hydroxy group-containing monomer(product name: 4HBA, solubility parameter: 11.6 (cal/cm3)1/2, molecularweight: 144, surface tension: 36.3 dyn/cm) from Nippon Kasei ChemicalCo., Ltd., and an acetoacetoxy group-containing monomer (product name:AAEM, solubility parameter: 10.6 (cal/cm3)1/2, molecular weight: 214,surface tension: 39.5 dyn/cm) from The Nippon Synthetic ChemicalIndustry Co., Ltd.

The solubility parameter as used herein is calculated by the Fedors'sestimation method described in Non Patent Literatures 1 and 2, whichestimates the solubility parameter from the molecular structure. Thesmaller the solubility parameter is, the higher the water repellencybecomes. The greater the solubility parameter is, the higher thehydrophilicity becomes.

The surface tension as used herein is determined by the penetration ratemethod. The penetration rate method is a method of pressing the targetsubstance into a column under a constant pressure to fill the column,and determining the surface tension of the target substance with waterfrom the equation: 12/t=(r·γ cos θ)/2η. In this equation, l representsthe penetration height of water, t represents time, r represents theradius of capillary of the filling target substance, γ represents thesurface tension, r_(i) represents the viscosity of water, and θrepresents the contact angle. The smaller the surface tension is, thegreater the contact angle becomes and the higher the water repellencybecomes.

The lower layer resin 3 may further contain a polymerization initiator.Examples of the polymerization initiator include photopolymerizationinitiators. The photopolymerization initiator is a compound that isactive to an active energy ray and is added to initiate thepolymerization reaction of polymerizing monomers. Thephotopolymerization initiator may be, for example, a radicalpolymerization initiator, an anionic polymerization initiator, or acationic polymerization initiator. Examples of the photopolymerizationinitiator include acetophenones such asp-tert-butyltrichloroacetophenone, 2,2′-diethoxyacetophenone, and2-hydroxy-2-methyl-1-phenylpropan-1-one; ketones such as benzophenone,4,4′-bisdimethylaminobenzophenone, 2-chlorothioxanthone,2-methylthioxanthone, 2-ethylthioxanthone, and 2-isopropylthioxanthone;benzoin ethers such as benzoin, benzoin methyl ether, benzoin isopropylether, and benzoin isobutyl ether; and benzyl ketals such as benzyldimethyl ketal and hydroxy cyclohexyl phenyl ketone. Known examples ofthe photopolymerization initiators include a photopolymerizationinitiator (product name: IRGACURE (registered trademark) 819) from BASFA.G.

The thickness DL (after application) of the lower layer resin 3 is notparticularly limited, but is preferably in the range of 3 μm to 30 μm,more preferably in the range of 5 μm to 7 μm.

The lower layer resin 3 preferably has a viscosity of higher than 10 cpand lower than 10000 cp at 25° C. In the case that the viscosity of thelower layer resin 3 is higher than 10 cp at 25° C., afluorine-containing monomer contained in the upper layer resin 4 can beprevented from being mixed into the lower layer resin 3 in the statewhere the lower layer resin 3 and the upper layer resin 4 are stacked,so that the concentration of fluorine atoms 7 in the vicinity of thesurface of the upper layer resin 4 can be suitably prevented fromdecreasing. In the case that the viscosity of the lower layer resin 3 islower than 10000 cp at 25° C., the applicability of the lower layerresin 3 can be suitably increased. The viscosity as used herein ismeasured using a model TV-25 viscometer (product name: TVE-25L) fromToki Sangyo Co., Ltd.

The upper layer resin 4 contains a fluorine-containing monomer. Thefluorine-containing monomer can reduce the surface free energy of theoptical film 1, and gives, when combined with the moth-eye structure,excellent anti-fouling properties to the optical film 1.

The fluorine-containing monomer preferably includes a moiety containingat least one selected from the group consisting of fluoroalkyl groups,fluorooxyalkyl groups, fluoroalkenyl groups, fluoroalkanediyl groups,and fluorooxyalkanediyl groups, and a reactive moiety.

The fluoroalkyl groups, fluorooxyalkyl groups, fluoroalkenyl groups,fluoroalkanediyl groups, and fluorooxyalkanediyl groups each are asubstituent in which at least one hydrogen atom in the akyl, oxyalkyl,alkenyl, alkanediyl, or oxyalkanediyl group is replaced by a fluorineatom. The fluoroalkyl groups, fluorooxyalkyl groups, fluoroalkenylgroups, fluoroalkanediyl groups, and fluorooxyalkanediyl groups each area substituent mainly containing fluorine atoms and carbon atoms, and mayhave a branched structure. A plurality of these substituents may beconnected.

The reactive moiety refers to a moiety that reacts with anothercomponent under an external energy such as light or heat. Examples ofsuch a reactive moiety include alkoxysilyl groups, silylether groups,silanol groups resulting from hydrolysis of alkoxysilyl groups, carboxylgroups, hydroxy groups, epoxy groups, vinyl groups, allyl groups,acryloyl groups, and methacryloyl groups. From the viewpoint of thereactivity and the handleability, the reactive moiety is preferably analkoxysilyl group, a silyl ether group, a silanol group, an epoxy group,a vinyl group, an allyl group, an acryloyl group, or a methacryloylgroup, more preferably a vinyl group, an allyl group, an acryloyl group,or a methacryloyl group, particularly preferably an acryloyl group or amethacryloyl group.

Examples of the fluorine-containing monomer include monomers representedby the following formula (A).

Rf1-R2-D1  (A)

In the formula (A), Rf1 represents a moiety containing at least oneselected from the group consisting of fluoroalkyl groups, fluorooxyalkylgroups, fluoroalkenyl groups, fluoroalkanediyl groups, andfluorooxyalkanediyl groups; R2 represents an alkanediyl group, analkanetriyl group, or the ester, urethane, ether, or triazine structurederived from any of these groups; and D1 represents a reactive moiety.

Examples of the monomers represented by the formula (A) include2,2,2-trifluoroethyl acrylate, 2,2,3,3,3-pentafluoropropyl acrylate,2-perfluorobutyl ethyl acrylate, 3-perfluorobutyl-2-hydroxypropylacrylate, 2-perfluorohexyl ethyl acrylate,3-perfluorohexyl-2-hydroxypropyl acrylate, 2-perfluorooctyl ethylacrylate, 3-perfluorooctyl-2-hydroxypropyl acrylate, 2-perfluorodecylethyl acrylate, 2-perfluoro-3-methylbutyl ethyl acrylate,3-perfluoro-3-methoxybutyl-2-hydroxypropyl acrylate,2-perfluoro-5-methylhexyl ethyl acrylate,3-perfluoro-5-methylhexyl-2-hydroxypropyl acrylate,2-perfluoro-7-methyloctyl-2-hydroxypropyl acrylate, tetrafluoropropylacrylate, octafluoropentyl acrylate, dodecafluoroheptyl acrylate,hexadecafluorononyl acrylate, hexafluorobutyl acrylate,2,2,2-trifluoroethyl methacrylate, 2,2,3,3,3-pentafluoropropylmethacrylate, 2-perfluorobutyl ethyl methacrylate,3-perfluorobutyl-2-hydroxypropyl methacrylate, 2-perfluorooctyl ethylmethacrylate, 3-perfluorooctyl-2-hydroxypropyl methacrylate,2-perfluorodecyl ethyl methacrylate, 2-perfluoro-3-methylbutyl ethylmethacrylate, 3-perfluoro-3-methylbutyl-2-hydroxypropyl methacrylate,2-perfluoro-5-methylhexyl ethyl methacrylate,3-perfluoro-5-methylhexyl-2-hydroxypropyl methacrylate,2-perfluoro-7-methyloctyl ethyl methacrylate, 3-perfluoro-7-methyloctylethyl methacrylate, tetrafluoropropyl methacrylate, octafluoropentylmethacrylate, dodecafluoroheptyl methacrylate, hexadecafluorononylmethacrylate, 1-trifluoromethyl trifluoroethyl methacrylate,hexafluorobutyl methacrylate, andtriacryloyl-heptadecafluorononenyl-pentaerythritol.

Examples of suitable materials of the fluorine-containing monomerinclude materials containing a fluoropolyether moiety. A fluoropolyethermoiety contains a group such as a fluoroalkyl group, an oxyfluoroalkylgroup, or an oxyfluoroalkyldiyl group, and is represented by thefollowing formula (B) or (C).

CFn1H(3-n1)-(CFn2H(2-n2))kO-(CFn3H(2-n3))mO-  (B)

-(CFn4H(2-n4))pO-(CFn5H(2-n5))sO-  (C)

In the formulas (B) and (C), n1 is an integer of 1 to 3, n2 to n5 eachare 1 or 2, and k, m, p, and s each are an integer of 0 or greater.Preferred combinations of n1 to n5 are combinations in which n1 is 2 or3 and n2 to n5 each are 1 or 2. More preferred combinations of n1 to n5are combinations in which n1 is 3, n2 and n4 each are 2, and n3 and n5each are 1 or 2.

The number of carbon atoms contained in the fluoropolyether moiety ispreferably in the range of 4 to 12, more preferably in the range of 4 to10, still more preferably in the range of 6 to 8. If the number ofcarbon atoms is less than 4, the surface energy may decrease. If thenumber of carbon atoms is more than 12, the solubility of the monomerinto the solvent may decrease. The fluorine-containing monomer mayinclude multiple fluoropolyether moieties per molecule.

Known examples of the fluorine-containing monomer include afluorine-based additive (product name: OPTOOL DAC-HP, solubilityparameter: 9.7 (cal/cm3)1/2) from Daikin Industries Ltd., afluorine-based additive (product name: OPTOOL DSX) from DaikinIndustries Ltd., a fluorine-based additive (product name: Afluid,solubility parameter: 9 to 11 (cal/cm3)1/2, surface tension: 11 dyn/cm)from Asahi Glass Co., Ltd., a fluorine-based additive (product name:MEGAFACE (registered trademark) RS-76-NS) from DIC Corporation, afluorine-based additive (product name: MEGAFACE RS-75) from DICCorporation, a fluorine-based additive (product name: C10GACRY) fromYushi-Seihin Co., Ltd., and a fluorine-based additive (product name:C8HGOL) from Yushi-Seihin Co., Ltd. Preferably, the fluorine-containingmonomer is curable by ultraviolet rays and contains an —OCF2- chainand/or ═NCO— chain.

The fluorine-containing monomer may be contained also in the lower layerresin 3. In this case, the concentration of the fluorine-containingmonomer in the upper layer resin 4 is preferably higher than that in thelower layer resin 3. It is particularly preferred that the lower layerresin 3 contains no fluorine-containing monomer.

The upper layer resin 4 preferably has a concentration of thefluorine-containing monomer of higher than 0% by weight and lower than20% by weight. In the case that the concentration of thefluorine-containing monomer is lower than 20% by weight, occurrence ofcloudiness due to a large amount of the fluorine-containing monomer canbe suitably prevented.

The upper layer resin 4 contains at least one kind of second monomerthat contains no fluorine atoms. Examples of such a second monomerinclude an amide group-containing monomer (product name: ACMO) from KJChemicals Corporation, an amide group-containing monomer (product name:HEAA) from KJ Chemicals Corporation, an amide group-containing monomer(product name: DEAA) from KJ Chemicals Corporation, a hydroxygroup-containing monomer (product name: CHDMMA) from Nippon KaseiChemical Co., Ltd., a hydroxy group-containing monomer (product name:4HBA) from Nippon Kasei Chemical Co., Ltd., and an acetoacetoxygroup-containing monomer (product name: AAEM) from The Nippon SyntheticChemical Industry Co., Ltd.

The thickness DU (after application) of the upper layer resin 4 is notparticularly limited, but is preferably in the range of 0.1 μm to 15 μm,more preferably in the range of 1 μm to 10 μm, still more preferably inthe range of 2 μm to 8 μm, particularly preferably in the range of 5 μmto 8 μm. In order to improve the smoothness (leveling properties) afterapplication, a fluorine-based surfactant (e.g. a fluorine-basedsurfactant (product name: SURFLON (registered trademark)S-232) from AGCSeimi Chemical Co., Ltd.) or a fluorine-based solvent (e.g.fluorine-based solvent (product name: Diluent ZV) from FluoroTechnologyCo., Ltd.) may further be added to the upper layer resin 4.

The upper layer resin 4 preferably has a viscosity of higher than 0.1 cpand lower than 100 cp at 25° C. In the case that the viscosity of theupper layer resin 4 is lower than 100 cp at 25° C., suitable fluidity ofthe fluorine-containing monomer contained in the upper layer resin 4 canbe achieved, so that the applicability of the upper layer resin 4 can besuitably improved. In the case that the viscosity of the upper layerresin 4 is higher than 0.1 cp at 25° C., the applicability of the upperlayer resin 4 can be suitably improved, so that the thickness of theupper layer resin 4 can be easily controlled.

The upper layer resin 4 preferably contains no solvent. That is, theupper layer resin 4 is preferably a non-solvent resin. In the case thata solvent is not added to the upper layer resin 4, an apparatus fordrying and removing the solvent is not necessary, and thus the apparatuscost can be suppressed. Also, since no solvent is used, the cost for thesolvent can be eliminated and the productivity can be improved. Incontrast, if a solvent is added to the upper layer resin 4, thefluorine-containing monomer may be mixed too well, which may decreasethe concentration of the fluorine atoms 7 in the vicinity of the surfaceof the optical film 1. Also, the volatility of the upper layer resin 4will be high, which may decrease the applicability.

At least one of the first monomer and the second monomer contains acompatible monomer that is compatible with the fluorine-containingmonomer, and is dissolved in the lower layer resin 3 and the upper layerresin 4. Thereby, the fluorine-containing monomer is concentrated in thevicinity of the surface of the optical film 1 while maintaining itscompatibility with the compatible monomer. As a result, theconcentration of the fluorine atoms 7 in the vicinity of the surface canbe increased. Here, in order to improve the adhesion between the lowerlayer resin 3 and the upper layer resin 4, it is important to achieve astate in which, when the resins come into contact with each other asmonomers, the resins are instantaneously mixed with each other in theinterface therebetween, and after polymerization, the monomercompositions continuously change such that the interface does not existtherebetween. The compatible monomer is added to form the resin layer 8in such a state by improving the compatibility between the lower layerresin 3 and the upper layer resin 4. The compatible monomer thereforegives excellent scratch resistance to the optical film 1.

Suitable as the compatible monomer is a reactive dilution monomer forphotocurable resins, for example. Examples of such a reactive dilutionmonomer include an amide group-containing monomer (product name: ACMO)from KJ Chemicals Corporation, an amide group-containing monomer(product name: HEAA) from KJ Chemicals Corporation, an amidegroup-containing monomer (product name: DEAA) from KJ ChemicalsCorporation, a hydroxy group-containing monomer (product name: CHDMMA)from Nippon Kasei Chemical Co., Ltd., a hydroxy group-containing monomer(product name: 4HBA) from Nippon Kasei Chemical Co., Ltd., and anacetoacetoxy group-containing monomer (product name: AAEM) from TheNippon Synthetic Chemical Industry Co., Ltd. Such a material cansuitably dissolve the fluorine-containing monomer. Also, such a materialis highly compatible with the base film 2 (e.g. TAC film). Hence, whensuch a material is added to the lower layer resin 3, the adhesionbetween the base film 2 and the lower layer resin 3 can be suitablyimproved. The compatible monomer preferably contains an acid amide bondin the molecule.

The solubility parameter of the fluorine-containing monomer ispreferably in the range of 5 (cal/cm3)1/2 to 11 (cal/cm3)1/2. Thesolubility parameter of a monomer component other than the compatiblemonomer in the lower layer resin 3 is preferably in the range of 7(cal/cm3)1/2 to 16 (cal/cm3)1/2. The solubility parameter of a monomercomponent other than the compatible monomer in the upper layer resin 4is preferably in the range of 7 (cal/cm3)1/2 to 16 (cal/cm3)1/2.

The solubility parameter of the compatible monomer is not particularlylimited and can be suitably selected. From the viewpoint of sufficientlyimproving the compatibility between the lower layer resin 3 and theupper layer resin 4, the solubility parameter is preferably in the rangeof 5 (cal/cm3)1/2 to 16 (cal/cm3)1/2, more preferably in the range of8.3 (cal/cm3)1/2 to 9.7 (cal/cm3)1/2, still more preferably in the rangeof 8.3 (cal/cm3)1/2 to 9.5 (cal/cm3)1/2. Since a compatible monomerhaving a lower solubility parameter has better compatibility with thefluorine-containing monomer, the range for the concentration of thefluorine-containing monomer in the upper layer resin 4 can be set wide.Hence, even when the concentration of the fluorine-containing monomer inthe upper layer resin 4 is high, disadvantages such as cloudiness andseparation of layers can be suppressed, and the appearance after curingof the upper layer resin 4 can be favorable.

In the case that the monomer component other than the compatible monomerin the lower layer resin 3 includes multiple monomers, the solubilityparameter of the monomer component other than the compatible monomer inthe lower layer resin 3 (or simply the solubility parameter of the lowerlayer resin) is the sum of values each obtained by multiplying thesolubility parameter of each monomer by the ratio by weight of themonomer to the whole monomer component other than the compatiblemonomer. In the case that the monomer component other than thecompatible monomer in the upper layer resin 4 includes multiplemonomers, the solubility parameter of the monomer component other thanthe compatible monomer in the upper layer resin (or simply thesolubility parameter of the upper layer resin) is the sum of values eachobtained by multiplying the solubility parameter of each monomer by theratio by weight of the monomer to the whole monomer component other thanthe compatible monomer. In the case that multiple fluorine-containingmonomers are contained, the solubility parameter of thefluorine-containing monomer is the sum of values each obtained bymultiplying the solubility parameter of each fluorine-containing monomerby the ratio by weight of the fluorine-containing monomer to all thefluorine-containing monomers. In the case that multiple compatiblemonomers are contained, the solubility parameter of the compatiblemonomer is the sum of values each obtained by multiplying the solubilityparameter of each compatible monomer by the ratio by weight of thecompatible monomer to all the compatible monomers.

The difference between the solubility parameter of the compatiblemonomer and the solubility parameter of the fluorine-containing monomeris preferably in the range of 0 (cal/cm3)1/2 to 4.0 (cal/cm3)1/2, morepreferably in the range of 0 (cal/cm3)1/2 to 3.0 (cal/cm3)1/2, stillmore preferably in the range of 0 (cal/cm3)1/2 to 2.5 (cal/cm3)1/2, fromthe viewpoint of sufficiently improving the compatibility between themonomers.

The difference between the solubility parameter of the compatiblemonomer and the solubility parameter of the monomer component other thanthe compatible monomer in the lower layer resin 3 is preferably in therange of 0 (cal/cm3)1/2 to 3.0 (cal/cm3)1/2, more preferably in therange of 0 (cal/cm3)1/2 to 2.0 (cal/cm3)1/2, from the viewpoint ofsufficiently improving the compatibility between the monomers.

The difference between the solubility parameter of the compatiblemonomer and the solubility parameter of the monomer component other thanthe compatible monomer in the upper layer resin 4 is preferably in therange of 0 (cal/cm3)1/2 to 3.0 (cal/cm3)1/2, more preferably in therange of 0 (cal/cm3)1/2 to 2.0 (cal/cm3)1/2, from the viewpoint ofsufficiently improving the compatibility between the monomers.

The difference between the solubility parameter of thefluorine-containing monomer and the solubility parameter of the monomercomponent other than the compatible monomer in the lower layer resin 3is preferably in the range of 3.0 (cal/cm3)1/2 to 5.0 (cal/cm3)1/2, fromthe viewpoint of suitably preventing the fluorine-containing monomercontained in the upper layer resin 4 from being mixed into the lowerlayer resin 3 in the state where the lower layer resin 3 and the upperlayer resin 4 are stacked, and eventually suitably preventing a decreasein the concentration of the fluorine atoms 7 in the vicinity of thesurface of the upper layer resin 4.

The difference between the solubility parameter of the base film 2 andthe solubility parameter of the monomer component other than thecompatible monomer in the lower layer resin 3 is preferably in the rangeof 0 (cal/cm3)1/2 to 5.0 (cal/cm3)1/2, from the viewpoint ofsufficiently improving the adhesion between these components.

The compatible monomer is contained in at least one of the first monomer(lower layer resin 3) and the second monomer (upper layer resin 4) inany of the following forms (i) to (iii), for example.

(i) Form in which the Compatible Monomer is Contained in the FirstMonomer and the Second Monomer

This form is effective when the difference between the solubilityparameter of the monomer component other than the compatible monomer inthe lower layer resin 3 and the solubility parameter of thefluorine-containing monomer is large (for example, 2.0 (cal/cm3)1/2 ormore). The compatible monomer contained in the first monomer and thecompatible monomer contained in the second monomer may have the samesolubility parameter or different solubility parameters. In the casethat these monomers have different solubility parameters, the solubilityparameter of the compatible monomer contained in the first monomer ispreferably greater than the solubility parameter of the compatiblemonomer contained in the second monomer. In the case that these monomershave the same solubility parameter, the compatible monomers may be thesame one whose solubility parameter is preferably an intermediate valuebetween the solubility parameter of the monomer component other than thecompatible monomer in the lower layer resin 3 and the solubilityparameter of the fluorine-containing monomer.

(ii) Form in which the Compatible Monomer is Contained Only in the FirstMonomer

The solubility parameter of the compatible monomer is preferably anintermediate value between the solubility parameter of the monomercomponent other than the compatible monomer in the lower layer resin 3and the solubility parameter of the fluorine-containing monomer.

(iii) Form in which the Compatible Monomer is Contained Only in theSecond Monomer

The solubility parameter of the compatible monomer is preferably anintermediate value between the solubility parameter of the monomercomponent other than the compatible monomer in the lower layer resin 3and the solubility parameter of the fluorine-containing monomer.

The mold 5 is pressed against the lower layer resin 3 and the upperlayer resin 4 to form the uneven structure (moth-eye structure). Themold 5 can be one produced by the following method, for example. First,a substrate is produced by sequentially forming, on an aluminum basematerial, a film of silicon dioxide (SiO2) as an insulating layer and afilm of pure aluminum. At this time, in the case that the aluminum basematerial is in a roll shape, the insulating layer and the pure aluminumlayer can be continuously formed. Next, the pure aluminum layer formedon the surface of the substrate is alternately repetitively anodized andetched, so that a female die (mold) having a moth-eye structure can beproduced.

The mold 5 has preferably been subjected to a release treatment. Whenthe mold 5 has been subjected to a release treatment, the surface freeenergy of the mold 5 can be lowered, and the fluorine-containing monomercan be suitably concentrated in the vicinity of the surface of the resinlayer 8 (upper layer resin 4) when the mold 5 is pressed against thelayer. The release treatment also suitably prevents thefluorine-containing monomer from moving away from the vicinity of thesurface of the resin layer 8 before the resin layer 8 is cured. As aresult, the concentration of the fluorine atoms 7 in the vicinity of thesurface of the optical film 1 can be suitably increased. The releasetreatment is preferably a surface treatment with a silane couplingagent. Suitable as the silane coupling agent is a fluorine-based silanecoupling agent.

As described above, the method for producing the optical film ofEmbodiment 1 enables formation of a moth-eye structure on the surfaceand formation of the resin layer 8 having an increased concentration ofthe fluorine atoms 7 in the vicinity of the surface and improvedadhesion between the lower layer resin 3 and the upper layer resin 4.Hence, an optical film excellent in anti-fouling properties and scratchresistance as well as anti-reflection properties can be produced.

Next, the optical film 1 produced by the above-described productionmethod is described below.

As illustrated in the view (d) of FIG. 1, the optical film 1 includesthe base film 2 and a cured product of the resin layer 8 in the givenorder. The optical film 1 corresponds to an anti-reflection film withthe projections provided at a pitch P equal to or shorter than thewavelength of visible light, i.e., an anti-reflection film having amoth-eye structure. Thereby, the optical film 1 can show excellentanti-reflection properties (low-reflection properties) with the moth-eyestructure.

Examples of the shape of the projections 6 include, but are notparticularly limited to, shapes that taper toward the end (taperedshapes) such as shapes formed by a pillar-shaped bottom portion and ahemispherical top portion (i.e. bell shapes) and conical shapes (coneshapes, circular cone shapes). Also, the projections 6 may have a shapewith branched projections. The branched projections refer to projectionsformed at an irregular pitch in the anodizing and etching for productionof the mold 5. In the view (d) of FIG. 1, the base of the gap betweeneach adjacent pair of the projections 6 has an inclined shape, but mayhave a horizontal shape without the inclination.

The pitch P of the adjacent projections 6 may be any pitch equal to orshorter than the wavelength (780 nm) of visible light, but from theviewpoint of achieving sufficient anti-fouling properties, the pitch Pis preferably in the range of 100 nm to 400 nm, more preferably in therange of 100 nm to 200 nm. The pitch of adjacent projections as usedherein refers to the average distance between all adjacent projectionsexcept for the branched projections in a 1-μm square region in a planephotograph taken by a scanning electron microscope (product name:S-4700) from Hitachi High-Technologies Corp. The pitch of adjacentprojections is measured in the state where osmium(VIII) oxide(thickness: 5 nm) from Wako Pure Chemical Industries, Ltd. has beenapplied to the uneven structure by an osmium coater (product name:Neoc-ST) from Meiwafosis Co., Ltd.

The height of the projections 6 is not particularly limited, but fromthe viewpoint of achieving a suitable aspect ratio of the projections 6at the same time as described below, the height is preferably in therange of 50 nm to 600 nm, more preferably in the range of 100 nm to 300nm. The height of projections as used herein refers to the averageheight of 10 consecutive adjacent projections except for branchedprojections in a cross-sectional photograph taken by a scanning electronmicroscope (product name: S-4700) from Hitachi High-Technologies Corp.Here, these 10 projections should exclude projections with defects ordeformed parts (e.g., parts deformed in preparation of a sample). Thesample used is obtained by sampling in a region of the optical filmwithout specific defects. For example, in the case that the optical filmis continuously produced in a roll shape, the sample used is sampledaround the center of the roll shape. The height of the projections ismeasured in the state where osmium(VIII) oxide (thickness: 5 nm) fromWako Pure Chemical Industries, Ltd. has been applied to the unevenstructure by an osmium coater (product name: Neoc-ST) from MeiwafosisCo., Ltd.

The aspect ratio of the projections 6 is not particularly limited, andis preferably in the range of 0.8 to 1.5. In the case that the aspectratio of the projections 6 is 1.5 or less, the processability of themoth-eye structure is sufficiently improved, which reduces the concernabout occurrence of sticking and poor transfer conditions (e.g.occurrence of clogging or winding in the mold 5) in formation of themoth-eye structure. In the case that the aspect ratio of the projections6 is 0.8 or more, optical phenomena such as moire and rainbow unevennesscan be sufficiently prevented, so that favorable reflection propertiescan be achieved. The aspect ratio of the projections as used hereinrefers to the ratio (height/pitch) of the pitch of adjacent projectionsand the height of the projections.

The arrangement of the projections 6 is not particularly limited, andmay be a random arrangement or regular arrangement. From the viewpointof sufficiently preventing occurrence of moire, a random arrangement ispreferred.

The surface of the optical film 1 preferably has a contact angle withwater of 100° or greater and a contact angle with hexadecane of 40° orgreater. In this case, an optical film having sufficiently high waterrepellency and oil repellency can be obtained. More preferably, thesurface of the optical film 1 has a contact angle with water of 150° orgreater and a contact angle with hexadecane of 90° or greater. In thiscase, an optical film having higher water repellency and higher oilrepellency, that is, super water repellency and super oil repellency,can be obtained. The contact angle with water is an index showing thelevel of water repellency. The greater the contact angle with water is,the higher the water repellency becomes. The contact angle withhexadecane is an index showing the level of oil repellency. The greaterthe contact angle with hexadecane is, the higher the oil repellencybecomes. The contact angle as used herein refers to the average contactangle at three sites each calculated by the θ/2 method (calculated fromthe equation θ/2=arctan(h/r) wherein θ represents a contact angle, rrepresents a radius of a droplet, and h represents the height of thedroplet) using a portable angle meter (product name: PCA-1) from KyowaInterface Science Co., Ltd. Here, the first measurement site is selectedto be the center portion of the sample, and the second and thirdmeasurement sites are selected to be two points that are away from thefirst measurement site by 20 mm or more and are symmetrical with thefirst measurement site.

Embodiment 2

FIG. 2 illustrates schematic cross-sectional views for explaining theprocess of producing an optical film of Embodiment 2 (steps a to c).Embodiment 2 is the same as Embodiment 1 except that the lower layerresin and the upper layer resin are simultaneously applied. Hence, thesame points are not described here.

(a) Application of Lower Layer Resin and Upper Layer Resin

First, as illustrated in the view (a) of FIG. 2, the lower layer resin 3and the upper layer resin 4 are simultaneously applied to the base film2 by the co-extrusion method. As a result, the upper layer resin 4 isformed on the lower layer resin 3 on the side opposite to the base film2.

(b) Formation of Uneven Structure

As illustrated in the view (b) of FIG. 2, in the state where the appliedlower layer resin 3 and upper layer resin 4 are stacked, the mold 5 ispressed against the lower layer resin 3 and the upper layer resin 4 fromthe upper layer resin 4 side, so that the resin layer 8 having an unevenstructure on a surface thereof is formed.

(c) Curing of Resin Layer

The resin layer 8 having the uneven structure is cured. As a result, theoptical film 1 including a cured product of the resin layer 8 having theuneven structure on the surface as illustrated in the view (c) of FIG. 2is completed.

The method for producing an optical film according to Embodiment 2enables production of an optical film excellent in anti-foulingproperties and scratch resistance as well as anti-reflection propertiesas in the case of the method for producing an optical film according toEmbodiment 1. Furthermore, since the lower layer resin 3 and the upperlayer resin 4 are simultaneously applied, the number of steps can bereduced compared to Embodiment 1.

Embodiment 3

FIG. 3 illustrates schematic cross-sectional views for explaining theprocess of producing an optical film of Embodiment 3 (steps a to c).Embodiment 3 is the same as Embodiment 1 except that the method forapplying the upper layer resin is changed. Hence, the same points arenot described here.

(a) Application of Lower Layer Resin and Upper Layer Resin

First, as illustrated in the view (a) of FIG. 3, the lower layer resin 3is applied to the base film 2. Meanwhile, the upper layer resin 4 isapplied to an uneven surface of the mold 5. Here, as illustrated in theview (a) of FIG. 3, the thickness DU (after application) of the upperlayer resin 4 in the present embodiment refers to the distance from aposition of the upper layer resin 4 corresponding to the bottom point ofa recess of the mold 5 to the surface of the upper layer resin 4 on theside opposite to the mold 5.

(b) Formation of Uneven Structure

As illustrated in the view (b) of FIG. 3, the mold 5 to which the upperlayer resin 4 has been applied is pressed from the upper layer resin 4side against the lower layer resin 3 applied to the base film 2, so thatthe upper layer resin 4 is stacked on the lower layer resin 3 and,simultaneously, an uneven structure is formed. As a result, the resinlayer 8 having the uneven structure on the surface is formed.

(c) Curing of Resin Layer

The resin layer 8 having the uneven structure is cured. As a result, theoptical film 1 including a cured product of the resin layer 8 having theuneven structure on the surface as illustrated in the view (c) of FIG. 3is completed.

The method for producing an optical film according to Embodiment 3enables production of an optical film excellent in anti-foulingproperties and scratch resistance as well as anti-reflection propertiesas in the case of the method for producing an optical film according toEmbodiment 1. Furthermore, since stacking of the upper layer resin 4 onthe lower layer resin 3 and formation of the uneven structure aresimultaneously performed, the number of steps can be reduced compared toEmbodiment 1. Also, when the mold 5 has been subjected to a releasetreatment, the fluorine-containing monomer contained in the upper layerresin 4 can be suitably concentrated on the mold 5 side, i.e., in thevicinity of the surface of the upper layer resin 4, before the upperlayer resin 4 is stacked on the lower layer resin 3. As a result, theconcentration of the fluorine atoms 7 in the vicinity of the surface ofthe optical film 1 can be more suitably increased.

In a mode in which the upper layer resin 4 is applied to the unevensurface of the mold 5 as in the present embodiment, in the case that theupper layer resin 4 contains a fluorine-containing monomer (e.g.fluorine-based additive (product name: OPTOOL DAC-HP) from DaikinIndustries, Ltd.) and a compatible monomer (e.g. amide group-containingmonomer (product name: ACMO) from KJ Chemicals Corporation), thesmoothness (leveling properties) of the upper layer resin 4 afterapplication can be effectively improved and the occurrence of cissing onthe mold 5 can be effectively prevented by adding a fluorine-basedsurfactant (e.g. fluorine-based surfactant (product name: SURFLON S-232)from AGC Seimi Chemical Co., Ltd.) or a fluorine-based solvent (e.g.fluorine-based solvent (product name: Diluent ZV) from FluoroTechnologyCo., Ltd.), which have a low surface tension, to the upper layer resin4. In this case, the ratio by weight of the fluorine-based surfactant orthe fluorine-based solvent to the upper layer resin 4 is preferably inthe range of 1% by weight to 200% by weight.

Hereinafter, the present invention will be described in more detailbased on examples and comparative examples which, however, are notintended to limit the scope of the present invention.

Example 1

An optical film was produced by the method for producing the opticalfilm of Embodiment 1. The production process was performed as describedbelow.

(a) Application of Lower Layer Resin

First, the lower layer resin 3 was applied to the base film 2 by a barcoater (product name: No. 03) from Daiichi Rika Co., Ltd. The base film2 and the lower layer resin 3 used were the following ones.

<Base Film 2>

A PET film (product name: COSMOSHINE (registered trademark) A4300) fromToyobo Co., Ltd. on which an easy adhesion treatment has been performed

The solubility parameter of the base film 2 was 10.7 (cal/cm3)1/2. Thethickness of the base film 2 was 75 μm.

<Lower Layer Resin 3>

A mixture of the following materials (the numerical values given to therespective materials are the concentrations of the respective materialsin the lower layer resin 3.)

-   -   Urethane acrylate (product name: UA-7100) from Shin-Nakamura        Chemical Co., Ltd.: 31% by weight    -   Polyfunctional acrylate (product name: ATM-35E) from        Shin-Nakamura Chemical Co., Ltd.: 40% by weight    -   Polyfunctional acrylate (product name: A-TMM-3LM-N) from        Shin-Nakamura Chemical Co., Ltd.: 27.5% by weight    -   Photopolymerization initiator (product name: IRGACURE 819) from        BASF A.G.: 1.5% by weight

The solubility parameter of the lower layer resin 3 (excluding thephotopolymerization initiator) was 10.5 (cal/cm3)1/2. The thickness DL(after application) of the lower layer resin 3 was 7 μm.

(b) Application of the Upper Layer Resin

The upper layer resin 4 was applied to the applied lower layer resin 3by an ultrasonic spray (product name of the nozzle: Vortex) fromSono-Tek Corporation. The upper layer resin 4 used was the followingone.

<Upper Layer Resin 4>

A mixture of the following materials (the numerical values given to therespective materials are the concentrations of the respective materialsin the upper layer resin 4.)

-   -   Fluorine-containing monomer: fluorine-based additive (product        name: OPTOOL DAC-HP) from Daikin Industries, Ltd.: 10% by weight    -   Compatible monomer: amide group-containing monomer (product        name: ACMO) from KJ Chemicals Corporation: 90% by weight

The “OPTOOL DAC-HP” used as the fluorine-containing monomer had a solidsconcentration of 10% by weight. The solubility parameter of thefluorine-containing monomer was 9.7 (cal/cm3)1/2. The solubilityparameter of the compatible monomer was 12.0 (cal/cm3)1/2. The thicknessDU (after application) of the upper layer resin 4 was 1.3 μm.

(c) Formation of Uneven Structure

In the state where the applied lower layer resin 3 and upper layer resin4 were stacked, the mold 5 was pressed against the lower layer resin 3and the upper layer resin 4 from the upper layer resin 4 side, so thatthe resin layer 8 having an uneven structure on the surface was formed.The mold 5 used was one produced by the following method.

<Mold 5>

First, a film of aluminum was formed on a glass substrate by sputtering.Next, an anodized layer provided with multiple fine holes (recesses)(the distance between the bottom points of adjacent holes was equal toor shorter than the wavelength of visible light) was formed by repeatinganodizing and etching alternately on the formed film of aluminum.Specifically, fine holes (recesses) each having a shape that becomessmaller toward the inside of the film of aluminum (tapered shape) wereformed by sequentially performing anodizing, etching, anodizing,etching, anodizing, etching, anodizing, etching, and anodizing(anodizing: five times, etching: four times). Thereby, the mold 5 havingan uneven structure was obtained. At this time, the uneven structure ofthe mold 5 can be changed by controlling the time for anodizing and thetime for etching. In the present example, the time for one anodizingprocess was 316 seconds, and the time for one etching process was 825seconds. Observation of the mold 5 with a scanning electron microscopefound that the pitch of the projections was 200 nm and the height of theprojections was 350 nm. The mold 5 was subjected to a release treatmentin advance with a fluorine-based additive (product name: OPTOOL DSX)from Daikin Industries Ltd.

(d) Curing of Resin Layer

The resin layer 8 having the uneven structure was cured by beingirradiated with ultraviolet rays (dose: 200 mJ/cm2) from the base film 2side by an UV lamp (product name: LIGHT HANMAR6J6P3) from Fusion UVSystems Inc. As a result, the optical film 1 including a cured productof the resin layer 8 having the uneven structure on the surface wascompleted. The surface specification of the optical film 1 is shownbelow.

Shape of the projections 6: Bell shapePitch P of the projections 6: 200 nmHeight of the projections 6: 200 to 250 nm

Example 2

An optical film was produced by the same production method as in Example1 except that the thickness DU (after application) of the upper layerresin 4 was 6.5 μm.

Example 3

An optical film was produced by the method for producing an optical filmaccording to Embodiment 3. The production process was performed asdescribed below.

(a) Application of Lower Layer Resin and Upper Layer Resin

First, the lower layer resin 3 was applied to the base film 2 by a barcoater (product name: No. 03) from Daiichi Rika Co., Ltd. Meanwhile, theupper layer resin 4 was applied to the uneven surface of the mold 5 byan ultrasonic spray (product name of the nozzle: Vortex) from Sono-TekCorporation. The base film 2, the lower layer resin 3, the upper layerresin 4, and the mold 5 used were the same as those used in Example 1.The thickness DL (after application) of the lower layer resin 3 was 7μm. The thickness DU (after application) of the upper layer resin 4 was1.3 μm.

(b) Formation of Uneven Structure

The mold 5 to which the upper layer resin 4 was applied was pressed fromthe upper layer resin 4 side against the lower layer resin 3 applied tothe base film 2, so that the upper layer resin 4 was stacked on thelower layer resin 3 and, simultaneously, the uneven structure wasformed.

(c) Curing of Resin Layer

The resin layer 8 having the uneven structure was cured by beingirradiated with ultraviolet rays (dose: 200 mJ/cm2) from the base film 2side by an UV lamp (product name: LIGHT HANMAR6J6P3) from Fusion UVsystems Inc. As a result, the optical film 1 including a cured productof the resin layer 8 having the uneven structure on the surface wascompleted. The surface specification of the optical film 1 is shownbelow.

Shape of the projections 6: Bell shapePitch P of the projections 6: 200 nmHeight of the projections 6: 200 to 250 nm

Example 4

An optical film was produced by the same production method as in Example3 except that the thickness DU (after application) of the upper layerresin 4 was 2.5 μm.

Example 5

An optical film was produced by the same production method as in Example3 except that the thickness DU (after application) of the upper layerresin 4 was 3.8 μm.

Example 6

An optical film was produced by the same production method as in Example3 except that the thickness DU (after application) of the upper layerresin 4 was 25.0 μm.

Example 7

An optical film was produced by the same production method as in Example3 except for changes in the material of the base film, the apparatusused for application of the upper layer resin, and the thickness of theupper layer resin.

The base film 2 used was a TAC film (product name: FUJITAC (registeredtrademark) TD80UL) from Fujifilm Corporation on which an easy adhesiontreatment has been performed. The solubility parameter of the base film2 was 11 (cal/cm3)1/2. The thickness of the base film 2 was 75 μm. Theapparatus used to apply the upper layer resin 4 was a bar coater(product name: No. 02) from Daiichi Rika Co., Ltd. The thickness DU(after application) of the upper layer resin 4 was 2 μm.

Example 8

An optical film was produced by the same production method as in Example7 except that the release treatment for the mold 5 was not performed inadvance and the thickness DL (after application) of the lower layerresin 3 was 6 μm.

Comparative Example 1

FIG. 4 illustrates schematic cross-sectional views for explaining theprocess of producing an optical film of Comparative Example 1 (steps ato d). The production process was performed as described below.

(a) Application of Lower Layer Resin

First, as illustrated in the view (a) of FIG. 4, a lower layer resin 103a was applied to a base film 102 by a bar coater (product name: No. 03)from Daiichi Rika Co., Ltd. The base film 102 and the lower layer resin103 a used were the following ones.

<Base Film 102>

A TAC film (product name: FUJITAC TD80UL) from Fujifilm Corporation onwhich an easy adhesion treatment has been performed

The thickness of the base film 102 was 75 μm.

<Lower Layer Resin 103 a>

A mixture of the following materials (the numerical values given to therespective materials are the concentrations of the respective materialsin the lower layer resin 103 a)

-   -   Urethane acrylate (product name: UA-7100) from Shin-Nakamura        Chemical Co., Ltd.: 31% by weight    -   Polyfunctional acrylate (product name: ATM-35E) from        Shin-Nakamura Chemical Co., Ltd.: 40% by weight    -   Polyfunctional acrylate (product name: A-TMM-3LM-N) from        Shin-Nakamura Chemical Co., Ltd.: 27.5% by weight    -   Photopolymerization initiator (product name: IRGACURE 819) from        BASF A.G.: 1.5% by weight

The thickness (after application) of the lower layer resin 103 a was 7μm.

(b) Formation of Uneven Structure

As illustrated in the view (b) of FIG. 4, a mold 105 was pressed againstthe applied lower layer resin 103 a, so that an uneven structure wasformed. The mold 105 used was produced by the following method.

<Mold 105>

First, a film of aluminum was formed on a glass substrate by sputtering.Next, an anodized layer provided with multiple fine holes (recesses)(the distance between the bottom points of adjacent holes was equal toor shorter than the wavelength of visible light) was formed by repeatinganodizing and etching alternately on the formed film of aluminum.Specifically, fine holes (recesses) each having a shape that becomessmaller toward the inside of the film of aluminum (tapered shape) wereformed by sequentially performing anodizing, etching, anodizing,etching, anodizing, etching, anodizing, etching, and anodizing(anodizing: five times, etching: four times). Thereby, the mold 105having an uneven structure was obtained. In the present comparativeexample, the time for one anodizing process was 316 seconds, and thetime for one etching process was 825 seconds. Observation of the mold105 with a scanning electron microscope found that the pitch of theprojections was 200 nm and the height of the projections was 350 nm. Themold 105 was subjected to a release treatment in advance by afluorine-based additive (product name: OPTOOL DSX) from DaikinIndustries Ltd.

(c) Curing of Lower Layer Resin

The lower layer resin 103 a having the uneven structure was cured bybeing irradiated with ultraviolet rays (dose: 200 mJ/cm2) from the basefilm 102 side by an UV lamp (product name: LIGHT HANMAR6J6P3) fromFusion UV Systems Inc. The surface of the cured lower layer resin 103 awas subjected to an oxygen (O2) plasma treatment, and a film of silicondioxide (SiO2) was formed on the lower layer resin 103 a by radiofrequency (RF) sputtering, whereby a silicon dioxide layer 109 wasformed. The thickness of the silicon dioxide layer 109 was 10 nm.

(d) Application of Upper Layer Resin

As illustrated in the view (d) of FIG. 4, an upper layer resin 104 wasvapor-deposited on the silicon dioxide layer 109 by the inductionheating method (degree of vacuum: 1×10−4 to 1×10−3 Pa). As a result, anoptical film 101 a was completed. The upper layer resin 104 used was afluorine-based additive (product name: OPTOOL DSX) containing fluorineatoms 107 from Daikin Industries, Ltd. The thickness of the upper layerresin 104 was 10 nm or less. The surface specification of the opticalfilm 101 a is shown below.

Shape of projections 106 a: Bell shapePitch Q1 of the projections 106 a: 200 nmHeight of the projections 106 a: 200 to 250 nm

Comparative Example 2

An optical film was produced by the same production method as inComparative Example 1 except that a film of silicon dioxide was notformed in order to eliminate the damage on the lower layer resin 103 ain formation of a film of silicon dioxide.

Comparative Example 3

FIG. 5 illustrates schematic cross-sectional views for explaining theprocess of producing an optical film of Comparative Example 3 (steps ato c). The production process was performed as described below.

(a) Application of Lower Layer Resin

First, as illustrated in the view (a) of FIG. 5, a lower layer resin 103b to which a fluorine-containing monomer containing fluorine atoms 107was added was applied to the base film 102 by a bar coater (productname: No. 03) from Daiichi Rika Co., Ltd. The base film 102 and thelower layer resin 103 b used were the following ones.

<Base film 102>

A TAC film (product name: FUJITAC TD80UL) from Fujifilm Corporation onwhich an easy adhesion treatment has been performed

The thickness of the base film 102 was 75 μm.

<Lower Layer Resin 103 b>

A mixture of the following materials (the numerical values given to therespective materials are the concentrations of the respective materialsin the lower layer resin 103 b)

-   -   Urethane acrylate (product name: UA-7100) from Shin-Nakamura        Chemical Co., Ltd.: 24.5% by weight    -   Polyfunctional acrylate (product name: ATM-35E) from        Shin-Nakamura Chemical Co., Ltd.: 32.0% by weight    -   Polyfunctional acrylate (product name: A-TMM-3LM-N) from        Shin-Nakamura Chemical Co., Ltd.: 22.0% by weight    -   Photopolymerization initiator (product name: IRGACURE 819) from        BASF A.G.: 1.5% by weight    -   Fluorine-containing monomer: fluorine-based additive (product        name: OPTOOL DAC-HP) from Daikin Industries, Ltd.: 20% by weight

The thickness (after application) of the lower layer resin 103 b was 7μm.

(b) Formation of Uneven Structure

As illustrated in the view (b) of FIG. 5, the mold 105 was pressedagainst the applied lower layer resin 103 b, so that an uneven structurewas formed. The mold 105 used was the same as that in ComparativeExample 1.

(c) Curing of Lower Layer Resin

As illustrated in the view (c) of FIG. 5, the lower layer resin 103 bhaving the uneven structure was cured by being irradiated withultraviolet rays (dose: 200 mJ/cm2) from the base film 102 side by an UVlamp (product name: LIGHT HANMAR6J6P3) from Fusion UV Systems Inc. As aresult, an optical film 101 b was completed. The surface specificationof the optical film 101 b is shown below.

Shape of projections 106 b: Bell shapePitch Q2 of the projections 106 b: 200 nmHeight of the projections 106 b: 200 to 250 nm

[Evaluation of Optical Film]

Evaluation results of the anti-reflection properties, anti-foulingproperties (water repellency, oil repellency, and wiping properties),scratch resistance, transparency, and slidability of the optical filmsof Examples 1 to 8 and Comparative Examples 1 to 3 are shown in Table 1.

The anti-reflection properties were evaluated based on the luminousreflectance (Y value) of the sample of each example. Specifically, thesurface of the sample of each example was irradiated with a light sourceat a polar angle of 5°, and the regular reflectance of the sample ofeach example at each wavelength of the incident light was measured. Thereflectance (Y value) at a wavelength of 550 nm was used as theevaluation index of anti-reflection properties. The reflectance wasmeasured by a spectrophotometer (product name: V-560) from Jasco Corp.for a wavelength range of 250 to 850 nm. The measurement of thereflectance was performed in the state where a black acrylic plate(product name: ACRYLITE (registered trademark) EX-502) from MitsubishiRayon Co., Ltd. was attached to the back surface (surface with no unevenstructure) of the sample of each example. The light source used wasilluminant C. One example of the measurement results of the reflectanceis shown in FIG. 6. FIG. 6 is a graph showing the measurement results ofthe reflectance in Example 7. In Example 7, the Y value at a wavelengthof 550 nm was 0.05%, a* was −0.03, and b* was −1.06. In the examples(Examples 1 to 6) in which a PET film on which an easy adhesiontreatment was performed was used as the base film 2, samples weredetermined to be at an acceptable level (having excellentanti-reflection properties) if the Y value at a wavelength of 550 nm was0.3% or less. In the examples (Examples 7 and 8, Comparative Examples 1to 3) in which a TAC film on which an easy adhesion treatment wasperformed was used as the base film 2 (102), samples were determined tobe at an acceptable level (having excellent anti-reflection properties)if the Y value at a wavelength of 550 nm was 0.2% or less.

The anti-fouling properties were evaluated based on the waterrepellency, oil repellency, and wiping properties of the sample of eachexample.

The water repellency was evaluated based on the contact angle with waterof the surface of the sample of each example. The method for measuringthe contact angle was as described above. Samples were determined to beat an acceptable level (having excellent water repellency) if thesamples had a contact angle with water of 100° or greater.

The oil repellency was evaluated based on the contact angle withhexadecane of the surface of the sample of each example. The method formeasuring the contact angle was as described above. Samples weredetermined to be at an acceptable level (having excellent oilrepellency) if the samples had a contact angle with hexadecane of 20° orgreater.

The wiping properties were evaluated based on whether the dirt adheringto the surface of the sample of each example was wiped off or not.Specifically, Nivea cream (registered trademark) from Nivea-Kao Co, Ltd.was applied to the surface of the sample of each example, and was leftto stand at a temperature of 25° C. and a humidity of 40 to 60% forthree days. Then, the sample of each example was wiped with a nonwovenfabric (product name: savina (registered trademark)) from KB Seiren,Ltd. in a certain one direction for 50 times, and whether the dirt waswiped off or not was observed under an illuminance of 100 1×. Theevaluation indexes used were as follows: excellent: the dirt was wipedoff perfectly, good: the dirt was wiped off but not perfectly, poor:most of the dirt was not wiped off, and bad: the dirt was not wiped offat all. Samples were determined to be at an acceptable level (havingexcellent wiping properties) if the samples showed an excellent or goodevaluation result.

By the evaluation methods described above, samples were evaluated ashaving excellent anti-fouling properties if the water repellency, oilrepellency, and wiping properties were determined to be at acceptablelevels.

The scratch resistance was evaluated based on the steel wool (SW)resistance of the sample of each example. Specifically, the surface ofthe sample of each example was rubbed with steel wool (product name:#0000) from Nippon Steel Wool Co., Ltd. in the state where apredetermined load was applied to the steel wool. The load level atwhich the surface was scratched was taken as the evaluation index ofscratch resistance. The surface was rubbed with steel wool using asurface property tester (product name: 14FW) from Shinto Scientific Co.,Ltd. as the test machine, with a stroke width of 30 mm, a rate of 100mm/s, and the number of times of rubbing of 10 times in a reciprocatingmanner. The existence of a scratch was visually observed under anilluminance of 100 1× (fluorescent lamps). Here, samples were determinedto be at an acceptable level (having excellent scratch resistance) ifthe steel wool resistance was 100 g or more.

The transparency was evaluated based on the haze (diffusivity) of thesample of each example. Specifically, the diffuse transmittance and thetotal light transmittance of the sample of each example were measured,and the haze calculated from the equation of haze (%)=100×(diffusetransmittance)/(total light transmittance) was taken as the evaluationindex of the transparency. The diffuse transmittance and total lighttransmittance were measured by a haze meter (product name: NDH2000) fromNippon Denshoku Industries Co., Ltd. Samples were determined to be at anacceptable level (having excellent transparency) if the haze was 1.0% orlower.

The slidability was evaluated by touch with a cotton stick. Theevaluation indexes used were excellent: very easily slidable, good:easily slidable, fair: slidable, and poor: not slidable. Here, sampleswere determined to be at an acceptable level (having excellentslidability) if the samples showed excellent, good, or fair evaluationresult.

TABLE 1 Anti-fouling properties Anti-reflection Water repellency Oilrepellency properties Contact angle with Contact angle with Scratchresistance Transparency Y value water hexadecane Wping SW resistanceHaze (%) (°) (°) properties (g) (%) Slidability Example 1 0.11 100 23Good 100 0.7 Fair Example 2 0.11 >150 90 Excellent 300 0.8 ExcellentExample 3 0.11 >150 75 Excellent 250 0.8 Excellent Example 4 0.10 >15094 Excellent 300 0.7 Excellent Example 5 0.10 >150 96 Excellent 300 0.7Excellent Example 6 0.11 >150 120 Excellent 300 1.2 Excellent Example 70.05 >150 100 Excellent 300 0.2 Excellent Example 8 0.05 110 70 Good 1000.2 Fair Comparative 0.05 >150 98 Bad 50 0.2 Good Example 1 Comparative0.05 >150 94 Poor 100 0.2 Good Example 2 Comparative 0.05 106 65 Good100 (Clouded) Fair Example 3

As shown in Table 1, Examples 1 to 8 were all excellent in anti-foulingproperties and scratch resistance as well as anti-reflection properties.Specially, Examples 2 to 8 were better in anti-fouling properties andscratch resistance, and in particular, Examples 6 and 7 were excellentin anti-fouling properties and scratch resistance. That is, from theviewpoint of achieving especially good anti-fouling properties andscratch resistance, the method for producing an optical film accordingto Embodiment 3 was found to be suitable. Also, in comparison betweenExample 1 and Example 3 in which the thicknesses of the upper layerresins 4 were the same (1.3 μm), Example 3 was better in anti-foulingproperties and scratch resistance. This result shows that, in the casethat the thicknesses of the upper layer resins 4 are the same, use ofthe method for producing an optical film according to Embodiment 3enables achievement of better anti-fouling properties and scratchresistance. Accordingly, the method for producing an optical filmaccording to Embodiment 3 can effectively achieve excellent anti-foulingproperties and excellent scratch resistance even when the upper layerresin 4 is thinly applied. Also, Examples 1 to 5, 7, and 8 were alsoexcellent in transparency and slidability.

In contrast, as shown in Table 1, since the upper layer resin 104 wasapplied to the cured lower layer resin 103 a in Comparative Examples 1and 2, the adhesion between the lower layer resin 103 a and the upperlayer resin 104 was low, the scratch resistance was inferior(Comparative Example 1), and the wiping properties were inferior(Comparative Examples 1 and 2). The concentration of thefluorine-containing monomer in Comparative Example 3 was made higherthan that in each of the other examples in order to improve theanti-fouling properties, but cloudiness was caused by the large amountof the fluorine-containing monomer.

[Study on Improvement of Anti-Fouling Properties]

As described above, the method for producing an optical film accordingto Embodiment 3 was found to be able to achieve even better anti-foulingproperties. In the following, preferred characteristics of optical filmshaving excellent anti-fouling properties are described based on studyexamples on optical films produced by the method for producing anoptical film according to Embodiment 3.

Study Example 1

An optical film was produced by the method for producing an optical filmaccording to Embodiment 3. The production process was performed asdescribed below.

(a) Application of Lower Layer Resin and Upper Layer Resin

First, the lower layer resin 3 was applied to the base film 2 by a barcoater (product name: No. 06) from Daiichi Rika Co., Ltd. The upperlayer resin 4 was applied to the uneven surface of the mold 5 by anelectrostatic spray (product name: PDS-D series) from Hamamatsu NanoTechnology Inc. The application voltage to the electrostatic nozzle was2.5 kV. The base film 2, the lower layer resin 3, and the upper layerresin 4 used were the following ones. The mold 5 used was the same asthat used in Example 1.

<Base Film 2>

A PET film (product name: COSMOSHINE A4300) from Toyobo Co., Ltd. onwhich an easy adhesion treatment has been performed

The thickness of the base film 2 was 60 μm.

<Lower Layer Resin 3>

A mixture of the following materials (the numerical values given to therespective materials are the concentrations of the respective materialsin the lower layer resin 3.)

-   -   Urethane acrylate (product name: UA-7100) from Shin-Nakamura        Chemical Co., Ltd.: 31% by weight    -   Polyfunctional acrylate (product name: ATM-35E) from        Shin-Nakamura Chemical Co., Ltd.: 40% by weight    -   Polyfunctional acrylate (product name: A-TMM-3LM-N) from        Shin-Nakamura Chemical Co., Ltd.: 27.5% by weight    -   Photopolymerization initiator (product name: IRGACURE 819) from        BASF A.G.: 1.5% by weight

The thickness DL (after application) of the lower layer resin 3 was 14μm.

<Upper Layer Resin 4>

A mixture of the following materials (the numerical values given to therespective materials are the concentrations of the respective materialsin the upper layer resin 4.)

-   -   Fluorine-containing monomer A: 10% by weight    -   Fluorine-containing monomer B: 40% by weight    -   Compatible monomer: amide group-containing monomer (product        name: ACMO) from KJ Chemicals Corporation: 50% by weight

The fluorine-containing monomer A was a mixture of 4-acryloyl morpholine(concentration: in the range of 75% to 85%) and perfluoro polyether(PFPE) (concentration: in the range of 15% to 25%) (the numerical valuesin the respective parentheses indicate the concentrations of therespective components in the fluorine-containing monomer A), and had asolids concentration of 20% by weight. The solids concentration of thefluorine-containing monomer A in the upper layer resin 4 was 2.2% byweight. The fluorine-containing monomer B was a fluorine-basedsurfactant described in Patent Literature 4. The application amount ofthe upper layer resin 4 to the mold 5 was 2.1 μl, and the applicationarea was 80 mm×70 mm. That is, the thickness (equivalent) of the upperlayer resin 4 was 0.375 μm.

(b) Formation of Uneven Structure

The mold 5 to which the upper layer resin 4 was applied was pressed fromthe upper layer resin 4 side against the lower layer resin 3 applied tothe base film 2, so that the upper layer resin 4 was stacked on thelower layer resin 3 and, simultaneously, the uneven structure wasformed.

(c) Curing of Resin Layer

The resin layer 8 having the uneven structure was cured by beingirradiated with ultraviolet rays from the base film 2 side for threeminutes using a video light (product name: VL-G151) from LPL Co., Ltd.(integrated amount of light: 54 mJ/cm2). As a result, the optical film 1including a cured product of the resin layer 8 having the unevenstructure on the surface (hereinafter, such a cured product is alsoreferred to as a cured resin layer) was completed. Observation with anoptical microscope found that the thickness of the cured resin layer was11.5 μm. The surface specification of the optical film 1 is shown below.

Shape of the projections 6: Bell shapePitch P of the projections 6: 200 nmHeight of the projections 6: 250 to 300 nm

Study Example 2

An optical film was produced by the same production method as in StudyExample 1 except that the application amount of the upper layer resin tothe mold was changed.

The application amount of the upper layer resin 4 to the mold 5 was 6.5μl, and the application area was 80 mm×70 mm. That is, the thickness(equivalent) of the upper layer resin 4 was 1.16 μm.

Study Example 3

An optical film was produced by the same production method as in StudyExample 1 except that the application amount of the upper layer resin tothe mold was changed.

The application amount of the upper layer resin 4 to the mold 5 was 13.3μl, and the application area was 80 mm×70 mm. That is, the thickness(equivalent) of the upper layer resin 4 was 2.38 μm.

Study Example 4

An optical film was produced by the same production method as in StudyExample 1 except that the application amount of the upper layer resin tothe mold was changed.

The application amount of the upper layer resin 4 to the mold 5 was 30.5μl, and the application area was 80 mm×70 mm. That is, the thickness(equivalent) of the upper layer resin 4 was 5.45 μm.

(Evaluation 1)

The anti-fouling properties (water repellency, oil repellency, andfingerprint wiping properties) of the optical films of Study Examples 1to 4 were evaluated. The evaluation results are shown in Table 2.

The water repellency was evaluated based on the contact angle with waterof the surface of the sample of each study example. The oil repellencywas evaluated based on the contact angle with hexadecane of the surfaceof the sample of each study example. The methods for measuring thecontact angles were as described above.

The fingerprint wiping properties were evaluated based on the ease ofwiping off the fingerprint on the surface of the sample of each studyexample. Specifically, a fingerprint was put on the surface of thesample of each study example, and the sample was left to stand at atemperature of 25° C. and a humidity of 40 to 60% for three days. Then,the sample of each study example was wiped with a nonwoven fabric(product name: savina) from KB Seiren, Ltd. in a certain one directionfor 50 times, and the sample was observed under an illuminance of 1001×. The ease of wiping off a fingerprint was evaluated in the increasingorder from A, B, C, and D (with D being the easiest to wipe off).

TABLE 2 Anti-fouling properties Water repellency Oil repellency Contactangle Contact angle Fingerprint with water with hexadecane wiping (°)(°) properties Study Example 1 43 10.7 A Study Example 2 143 10.2 BStudy Example 3 159 34.1 C Study Example 4 162 94.7 D

As shown in Table 2, the highest anti-fouling properties were observedin Study Example 4, followed by Study Example 3, Study Example 2, andStudy Example 1 in the given order. That is, the larger the applicationamount of the upper layer resin 4 to the mold 5 (the thicker the upperlayer resin 4) is, the better the anti-fouling properties become. Incomparison between Study Example 1 and Study Example 2, the oilrepellencies were substantially the same as each other, but thefingerprint wiping properties of Study Example 2 were higher than thosein Study Example 1. This is presumably because, since fingerprintscontain not only oil but also moisture, the fingerprint wipingproperties depend also on the water repellency (Study Example 2 showedbetter water repellency than Study Example 1).

(Evaluation 2)

Measurements by X-ray photoelectron spectroscopy (XPS) were performed onthe surfaces of the optical films of Study Examples 1 to 4, i.e., thesurfaces of the uneven structures. The X-ray photoelectron spectroscopycan analyze the atomic composition and chemical bonding state (bindingspecies) of constituent atoms of a sample by irradiating the surface ofthe sample with X-rays and measuring the kinetic energy of thephotoelectrons ejected from the surface. The measurement device used wasan X-ray photoelectron spectroscopy instrument (product name: PHI 5000VersaProbe II) from Ulvac-Phi, Inc., and the specification of theinstrument is as described below.

<Device Specification>

-   -   X-ray source: monochromatized AlKα radiation (1486.6 eV)    -   Spectroscope: electrostatic concentric hemispherical analyzer    -   Amplifier: multi-channel type

FIG. 7 is a graph showing survey spectra of the surfaces of opticalfilms of Study Examples 1 to 4. The “c/s” on the vertical axis in FIG. 7is the abbreviation for “counts/seconds”. This also applies to the otherdrawings. The measurement conditions of the survey spectrum were asdescribed below.

<Measurement Conditions>

-   -   X-ray beam diameter: 100 μm (25 W, 15 kV)    -   Analysis area: 1000 μm×500 μm    -   Photoelectron extraction angle: 45°    -   Path energy: 187.85 eV

As illustrated in FIG. 7, the optical film of each of Study Examples 1to 4 showed the C1s peak, N1s peak, O1s peak, and F1s peak. That is, thecured resin layers of the optical films of Study Examples 1 to 4 werefound to contain carbon atoms, nitrogen atoms, oxygen atoms, andfluorine atoms as the constituent atoms.

Next, from the results shown in FIG. 7, the proportion of the number ofatoms of each kind relative to the total number of carbon atoms,nitrogen atoms, oxygen atoms, and fluorine atoms on the surface havingthe uneven structure was calculated. The calculation results are shownin Table 3. The surface having the uneven structure as used hereinrefers to a region that is within 6 nm from the outermost surface havingthe uneven structure in the depth direction.

TABLE 3 C1s N1s O1s F1s (atom %) (atom %) (atom %) (atom %) StudyExample 1 58.54 1.77 23.05 16.64 Study Example 2 45.35 1.78 19.24 33.63Study Example 3 39.15 2.23 14.78 43.84 Study Example 4 36.15 1.26 14.5748.02

As shown in Table 3, the proportion of the number of fluorine atomsrelative to the total number of carbon atoms, nitrogen atoms, oxygenatoms, and fluorine atoms on the surface having the uneven structure(hereinafter, such a proportion is also referred to as a fluorinecontent) was found to be the highest in Study Example 4, followed byStudy Example 3, Study Example 2, and Study Example 1 in the givenorder, and to have a strong correlation with the anti-fouling propertiesshown in Table 2. That is, as the application amount of the upper layerresin 4 to the mold 5 increases (as the thickness of the upper layerresin 4 increases), the fluorine content on the surface having theuneven structure increases, and thus the anti-fouling properties areimproved. The fluorine content on the surface having the unevenstructure is preferably 16 atom % or higher, more preferably 33 atom %or higher, still more preferably 43 atom % or higher, particularlypreferably 48 atom % or higher. The upper limit for the fluorine contenton the surface having the uneven structure is preferably 55 atom %, morepreferably 50 atom %. If the fluorine content on the surface having theuneven structure is higher than 55 atom %, the cured rein layer may beclouded.

Here, the results obtained by converting the unit of each numericalvalue “atom %” shown in Table 3 to “mass %” are shown in Table 4.

TABLE 4 C1s N1s O1s F1s (mass %) (mass %) (mass %) (mass %) StudyExample 1 49.77 1.75 26.10 22.38 Study Example 2 35.92 1.64 20.30 42.14Study Example 3 29.94 1.99 15.05 53.02 Study Example 4 27.18 1.11 14.5957.12

Table 3 of Non Patent Literature 3 shows the state where theconcentration of fluorine atoms on the surface was increased. However,as shown in Table 4, the optical films of Study Examples 2 to 4 canachieve a state where the concentration of fluorine atoms on the surfaceis higher than that in the state shown in Non Patent Literature 3.

The results obtained in Evaluation 1 and Evaluation 2 can be summarizedin terms of the application amount of the upper layer resin 4 to themold 5, that is, the thickness of the upper layer resin 4, as shown inFIGS. 8 and 9. FIG. 8 is a graph showing the relation between thethickness of an upper layer resin and the contact angle. FIG. 9 is agraph showing the relation between the thickness of an upper layer resinand the proportion of the number of fluorine atoms relative to the totalnumber of carbon atoms, nitrogen atoms, oxygen atoms, and fluorine atomson the surface having an uneven structure.

Comparison between FIG. 8 and FIG. 9 shows that the tendency of thecontact angle with water relative to the thickness of the upper layerresin 4 and the tendency of the fluorine content on the surface havingthe uneven structure relative to the thickness of the upper layer resin4 are similar to each other. That is, as the fluorine content on thesurface having the uneven structure increases, the contact angle withwater increases, and thus the water repellency is improved. Meanwhile,the tendency of the contact angle with hexadecane relative to thethickness of the upper layer resin 4 is considered to be related notonly to the fluorine content on the surface having the uneven structurerelative to the thickness of the upper layer resin 4 but also to theother factors.

(Evaluation 3)

The narrow spectra of the surfaces of the optical films of StudyExamples 1 to 4 were measured by the X-ray photoelectron spectroscopy,and the correlation between the tendency of the contact angle withhexadecane relative to the thickness of the upper layer resin 4 and thebinding species including fluorine atoms was studied.

FIG. 10 includes graphs showing narrow spectra of the surfaces of theoptical films of Study Examples 1 to 4, for (a) C1s peaks, (b) N1speaks, (C) O1s peaks, and (d) F1s peaks. The measurement conditions ofthe narrow spectra were as described below.

-   -   X-ray beam diameter: 100 μm (25 W, 15 kV)    -   Analysis area: 1000 μm×500 μm    -   Photoelectron extraction angle: 45°    -   Path energy: 46.95 eV

Next, the peak in each narrow spectrum obtained was separated intomultiple peaks, and the binding species of the respective peaks wereidentified from the peak positions and shapes. In the following, theanalysis results of the C1s peak and the O1s peak in Study Example 4 areshown. The same analysis was also carried out for the other studyexamples.

FIG. 11 is a graph showing an analysis result of the C1s peak in StudyExample 4 shown in the graph (a) of FIG. 10. In FIG. 11, the peak CRcorresponds to the C1s peak in Study Example 4 shown in the graph (a) ofFIG. 10. Meanwhile, the peaks C1 to C7 are spectra obtained bycurve-fitting for the peak CR (C1s peak) with the peak attributed toeach binding species. Also, the obtained spectra were subjected toelectrification correction so that the position of the peak C1 was 284.6eV.

The positions of the peaks C1 to C7 and the identified binding speciesare shown in Table 5. The binding species were identified using theinformation shown in Non Patent Literature 4 and Table 1 shown in NonPatent Literature 5.

TABLE 5 Peak position (eV) Binding species C1 284.6 C—C bonds and othersC2 285.8 C—O bonds, C—N bonds, and others C3 286.6 C4 288.4 CHF bonds,COO bonds, and others C5 289.1 C6 291.9 to 292.1 CF₂ bonds C7 293.3 to293.5 CF₃ bonds and OCF₂ bonds

As shown in Table 5, the peak C7 was identified as being attributed to“the CF3 bonds and OCF2 bonds”. Since the peak attributed to the CF3bonds and the peak attributed to the OCF2 bonds are at substantially thesame position as shown in Table 1 in Non Patent Literature 5, it hasbeen difficult to separate the peak C7 into these peaks.

FIG. 12 is a graph showing an analysis result of the O1s peak in StudyExample 4 shown in the graph (c) of FIG. 10. In FIG. 12, the peak ORcorresponds to the O1s peak in Study Example 4 shown in the graph (c) ofFIG. 10. Meanwhile, the peaks O1 to O3 are spectra obtained bycurve-fitting for the peak OR (O1s peak) with the peak attributed toeach binding species.

The positions of the peaks O1 to O3 and the identified binding speciesare shown in Table 6. The binding species were identified using theinformation shown in Non Patent Literature 6.

TABLE 6 Peak position (eV) Binding species O1 532.1 to 532.3 C—O bondsO2 533.6 to 533.7 C═O bonds O3 535.8 to 536.0 OF_(x) bonds

As shown in Table 6, the peak O3 was identified as being attributed tothe “OFx bonds”, but was found to be attributed to the OCF2 bondsaccording to FIG. 2 shown in Non Patent Literature 7. The OCF2 bonds arecontained in PFPE which is a component of the fluorine-containingmonomer A, for example. The peak attributed to the OCF2 bonds in PFPE isshifted to the higher energy side than usual.

As described above, the peaks in the narrow spectra on the surfaces ofthe optical films of Study Examples 1 to 4 each were separated into apeak (peak C6) attributed to the CF2 bonds, a peak (peak C7) attributedto the CF3 bonds and the OCF2 bonds, a peak (peak O3) attributed to theOCF2 bonds, and peaks attributed to the other binding species.

Next, the ratio of the peak area of each of the peak (peak C6)attributed to the CF2 bonds, the peak (peak C7) attributed to the CF3bonds and the OCF2 bonds, and the peak (peak O3) attributed to the OCF2bonds to the peaks attributed to the other binding species wascalculated in each study example. The peak area was calculated usingdata analysis software (product name: MultiPak) from the Ulvac-Phi, Inc.

FIG. 13 is a graph showing the relation between the thickness of anupper layer resin and the ratio of the peak area of the CF2 bonds to thepeak areas of binding species other than the CF2 bonds in the C1s peak.The specification of the data points in FIG. 13 is as described below.

-   -   “∘”: the ratio of the peak area of the CF2 bonds (area of peak        C6) to the peak area of the C—C bonds and others (area of peak        C1)    -   “□”: the ratio of the peak area of the CF2 bonds (area of peak        C6) to the peak area of the C—O bonds, C—N bonds, and others        (sum of the area of peak C2 and the area of peak C3)    -   “Δ”: the ratio of the peak area of the CF2 bonds (area of peak        C6) to the peak area of the CHF bonds, COO bonds, and others        (sum of the area of peak C4 and the area of peak C5)

In FIG. 13, “∘” and “□” are plotted along the left vertical axis, and“Δ” is plotted along the right vertical axis.

FIG. 14 is a graph showing the relation between the thickness of anupper layer resin and the ratio of the peak area of CF3 bonds and OCF2bonds to the peak areas of binding species other than the CF3 bonds andthe OCF2 bonds in the C1s peak. The specification of the data points inFIG. 14 is as described below.

-   -   “∘”: the ratio of the peak area of the CF3 bonds and the OCF2        bonds (area of peak C7) to the peak area of the C—C bonds and        others (area of peak C1)    -   “□”: the ratio of the peak area of the CF3 bonds and the OCF2        bonds (area of peak C7) to the peak area of the C—O bonds, C—N        bonds and others (sum of the area of peak C2 and the area of        peak C3)    -   “Δ”: the ratio of the peak area of the CF3 bonds and the OCF2        bonds (area of peak C7) to the peak area of the CHF bonds, COO        bonds, and others (sum of the area of peak C4 and the area of        peak C5)

In FIG. 14, “∘” and “□” are plotted along the left vertical axis, and“Δ” is plotted along the right vertical axis.

FIG. 15 is a graph showing the relation between the thickness of anupper layer resin and the ratio of the peak area of OCF2 bonds to thepeak areas of binding species other than the OCF2 bonds in the O1s peak.In FIG. 15, “∘” indicates the ratio of the peak area of the OCF2 bonds(area of peak O3) to the sum of the peak area of the C—O bonds (area ofpeak O1) and the peak area of the C═O bonds (area of peak O2). As shownin FIG. 15, the ratio of the peak area of the OCF2 bonds to the sum ofthe peak area of the C—O bond and the peak area of the C═O bonds is0.102 in Study Example 1 (thickness of the upper layer resin 4: 0.375μm), 0.355 in Study Example 2 (thickness of the upper layer resin 4:1.16 μm), 0.696 in Study Example 3 (thickness of the upper layer resin4: 2.38 μm), and 1.027 in Study Example 4 (thickness of the upper layerresin 4: 5.45 μm).

Comparison between FIG. 8 and FIGS. 13 to 15 shows that the tendency ofthe contact angle with hexadecane relative to the thickness of the upperlayer resin 4 has the strongest correlation with the ratio of the peakarea of the OCF2 bonds to the sum of the peak area of the C—O bonds andthe peak area of the C═O bonds as shown in FIG. 15. These results showthat as the ratio of the peak area of the OCF2 bonds to the sum of thepeak area of the C—O bonds and the peak area of the C═O bonds increases,the contact angle with hexadecane increases, so that the oil repellencyis improved. The ratio of the peak area of the OCF2 bonds to the sum ofthe peak area of the C—O bonds and the peak area of the C═O bonds ispreferably 0.1 or more, more preferably 0.3 or more, still morepreferably 0.6 or more, particularly preferably 1 or more. The upperlimit for the ratio of the peak area of the OCF2 bonds to the sum of thepeak area of the C—O bonds and the peak area of the C═O bonds ispreferably 1.1.

(Evaluation 4)

In order to determine the distribution states of the constituent atomsin the cured resin layers in the optical films of Study Examples 1 to 4,the X-ray photoelectron spectroscopy was performed while the unevenstructure was etched with gas cluster ion beams (GLIB).

A gas cluster ion beam consists of tens to thousands of atoms and hasvery low energy per atom. For example, an argon gas cluster ion beamleaves no residues of sputtered atoms when sputtered onto the sample,and thus can achieve ultra-low energy ion etching at about 1 to 20 eVper atom which cannot be achieved by C60 ions. Also, the beam enablesetching on an organic substance because almost no chemical change iscaused by argon gas cluster ions on the sample surface after sputtering.The measurement device used was obtained by installing an argon gascluster sputter ion gun (production name: 06-2000) from Ulvac-Phi, Inc.in an X-ray photoelectron spectroscopy instrument (product name: PHI5000 VersaProbe II) from Ulvac-Phi, Inc.

FIG. 16 is a graph showing the proportions of the numbers of therespective atoms relative to the total number of carbon atoms, nitrogenatoms, oxygen atoms, and fluorine atoms in a cured resin layer of theoptical film of Study Example 1. FIG. 17 is a graph showing theproportions of the numbers of the respective atoms relative to the totalnumber of carbon atoms, nitrogen atoms, oxygen atoms, and fluorine atomsin a cured resin layer of the optical film of Study Example 2. FIG. 18is a graph showing the proportions of the numbers of the respectiveatoms relative to the total number of carbon atoms, nitrogen atoms,oxygen atoms, and fluorine atoms in a cured resin layer of the opticalfilm of Study Example 3. FIG. 19 is a graph showing the proportions ofthe numbers of the respective atoms relative to the total number ofcarbon atoms, nitrogen atoms, oxygen atoms, and fluorine atoms in acured resin layer of the optical film of Study Example 4.

The sputtering conditions by argon gas cluster ion beams and the chargeneutralization conditions were as described below. The measurementconditions by X-ray photoelectron spectroscopy were the same as themeasurement conditions of the narrow spectra in Evaluation 3.

<Sputtering Conditions>

-   -   Ion source: argon gas cluster ion beams    -   Accelerating voltage: 10 kV (15 mA Emission)    -   Sample current: 30 nA    -   Raster area: 4 mm×3 mm    -   Zalar rotation: not used    -   Sputtering time: 81 minutes (total time of 1.5 minutes×two        cycles, 3 minutes×8 cycles, and 6 minutes×9 cycles)    -   Sputtering rate (etching rate): 27 nm/min (polyhydroxy styrene        equivalent)

<Charge Neutralization Conditions>

-   -   Electron gun: Bias 1.0 V (20 μA Emission)    -   Ion gun: 3 V (7 mA Emission)

The horizontal axis D (unit: μm) in FIGS. 16 to 19 indicates thedistance from the surface having the uneven structure in the depthdirection and is in terms of polyhydroxy styrene equivalent. Thevertical axis “atomic concentration” in FIGS. 16 to 19 indicates theproportion of the number of atoms of each kind (unit: atom %) relativeto the total number of carbon atoms, nitrogen atoms, oxygen atoms, andfluorine atoms.

As shown in FIGS. 16 to 19, the proportion (fluorine content) of thenumber of fluorine atoms to the total number of carbon atoms, nitrogenatoms, oxygen atoms, and fluorine atoms was found to decrease in thedepth direction of the cured resin layer. That is, the fluorine contentwas found to be high on the surface side of the cured resin layer(surface side of the uneven structure).

Next, the concentration of fluorine atoms in the cured resin layer wascalculated. The calculation results are shown in Table 7. Theconcentration of fluorine atoms in the cured resin layer was calculatedfor the cases of FIGS. 16 to 19 from the following formula.[Concentration of fluorine atoms in cured resin layer] (unit: %)=[areaof profile of fluorine atoms]/[area of plotting area]

Here, the [area of plotting area] specifically refers to a product ofthe length (11.5 μm: thickness of cured resin layer) of the horizontalaxis range and the length (100%) of the vertical axis range.

TABLE 7 Concentration of fluorine atoms in cured resin layer StudyExample 1 0.26 Study Example 2 0.63 Study Example 3 0.85 Study Example 41.06

As shown in Table 7, the concentration of fluorine atoms in the curedresin layer was about 1% at the highest, and the transparency was high.In contrast, as shown in Table 3, the fluorine content on the surfacehaving the uneven structure was high, showing that the fluorine atomswere contained on the surface side of the cured resin layer (surfaceside of the uneven structure) at a high concentration. Hence, theoptical films of Study Examples to 4 can achieve both transparency andanti-fouling properties. Also, the concentration of fluorine atoms inthe cured resin layer is preferably 2% or lower, more preferably 1.1% orlower. If the concentration of fluorine atoms in the cured resin layeris higher than 2%, the cured resin layer may be clouded.

(Evaluation 5)

Based on the results obtained in Evaluation 4, the distribution state offluorine atoms in the cured resin layer was studied in more detail. FIG.20 is a graph showing the distribution states of fluorine atoms in thecured resin layers of the optical films of Study Examples 1 to 4. Thesputtering conditions by argon gas cluster ion beams, chargeneutralization conditions, and the measurement conditions of the X-rayphotoelectron spectroscopy were the same as those in Evaluation 4.

The horizontal axis D (unit: nm) in FIG. 20 indicates the distance fromthe surface having the uneven structure in the depth direction and is interms of polyhydroxy styrene equivalent. The vertical axis “MFD/MFS” inFIG. 20 indicates the ratio of MFD to MFS defined as described below.

-   -   MFS (unit: atom %): the proportion of the number of fluorine        atoms relative to the total number of carbon atoms, nitrogen        atoms, oxygen atoms, and fluorine atoms on the surface having        the uneven structure    -   MFD (unit: atom %): the proportion of the number of fluorine        atoms relative to the total number of carbon atoms, nitrogen        atoms, oxygen atoms, and fluorine atoms at a position away from        the surface having the uneven structure by D (unit: nm) in the        depth direction in terms of polyhydroxy styrene equivalent

As shown in FIG. 20, the proportion (fluorine content) of the number offluorine atoms relative to the total number of carbon atoms, nitrogenatoms, oxygen atoms, and fluorine atoms was found to decrease in thedepth direction of the cured resin layer. The decreasing tendency of thefluorine content was found to be the slowest in Study Example 4,followed by Study Example 3, Study Example 2, and Study Example 1 in thegiven order. That is, as the application amount of the upper layer resin4 to the mold 5 increases (as the thickness of the upper layer resin 4increases), the distribution range of the fluorine atoms was found to bedeeper in the cured resin layer. The D satisfying the equation MFD/MFS=0was 1050 nm or more in Study Example 1, 1220 nm or more in Study Example2, 1380 nm or more in Study Example 3, and 1540 nm or more in StudyExample 4. As shown in FIG. 20, the D satisfying the equationMFD/MFS=0.3 was 200 nm in Study Example 1, 240 nm in Study Example 2,275 nm in Study Example 3, and 350 nm in Study Example 4. The Dsatisfying the equation MFD/MFS=0.3 is preferably 200 nm or more, morepreferably 240 nm or more, still more preferably 275 nm or more,particularly preferably 350 nm or more. In the case that the Dsatisfying the equation MFD/MFS=0.3 is 240 nm or more, more fluorineatoms are entirely distributed in the inner portions of the projections6 of the uneven structure (height of projections 6: 250 nm to 300 nm),and the anti-fouling properties are sufficiently improved. The upperlimit for the D satisfying the equation MFD/MFS=0.3 is preferably 350nm.

(Evaluation 6)

Evaluation 5 revealed the distribution state of fluorine atoms in thecured resin layer. Next, the distribution state of components (CF2bonds, CF3 bonds, and OCF2 bonds) contained in the fluorine-containingmonomer A and the fluorine-containing monomer B in the cured resin layerwas studied by separating the peak of each spectrum in the depthdirection of the cured resin layer into peaks attributed to therespective binding species.

FIG. 21 is a graph showing the distribution states of CF2 bonds in thecured resin layers of the optical films of Study Examples 1 to 4. Thehorizontal axis D (unit: nm) in FIG. 21 indicates the distance from thesurface having the uneven structure in the depth direction, and is interms of polyhydroxy styrene equivalent. The vertical axis “M1D/M1S” inFIG. 21 indicates the ratio of M1D to MIS as defined below.

-   -   M1S: peak area of the CF2 bonds in C1s peak detected on the        surface having the uneven structure    -   M1D: peak area of the CF2 bonds in the C1s peak detected at a        position away from the surface having the uneven structure by D        (unit: nm) in the depth direction in terms of polyhydroxy        styrene equivalent

Here, the peak attributed to the CF2 bonds was analyzed as a peakcorresponding to the peak separated from the C1s peak (e.g. peak C6 inFIG. 11).

As shown in FIG. 21, the amount of the CF2 bonds was found to decreasein the depth direction of the cured resin layer. The decreasing tendencyof the amount of CF2 bonds was found to be the slowest in Study Example4, followed by Study Example 3, Study Example 2, and Study Example 1 inthe given order. That is, as the application amount of the upper layerresin 4 to the mold 5 increases (as the thickness of the upper layerresin 4 increases), the distribution range of the CF2 bonds was found tobe deeper in the cured resin layer.

FIG. 22 is a graph showing the distribution states of CF3 bonds and OCF2bonds in the cured resin layers of the optical films of Study Examples 1to 4. The horizontal axis D (unit: nm) in FIG. 22 indicates the distancefrom the surface having the uneven structure in the depth direction andis in terms of polyhydroxy styrene equivalent. The vertical axis“M2D/M2S” in FIG. 22 indicates the ratio of M2D to M2S as defined below.

-   -   M2S: peak area of the CF3 bonds and OCF2 bonds in C1s peak        detected on the surface having the uneven structure    -   M2D: peak area of the CF3 bonds and OCF2 bonds in the C1s peak        detected at a position away from the surface having the uneven        structure by D (unit: nm) in the depth direction in terms of        polyhydroxy styrene equivalent

Here, the peak attributed to the CF3 bonds and the OCF2 bonds wasanalyzed as a peak corresponding to the peak separated from the C1s peak(e.g. peak C7 in FIG. 11).

As shown in FIG. 22, the amount of the CF3 bonds and the OCF2 bonds wasfound to decrease in the depth direction of the cured resin layer. Thedecreasing tendency of the amount of CF3 bonds and the OCF2 bonds wasfound to be the slowest in Study Example 4, followed by Study Example 3,Study Example 2, and Study Example 1 in the given order. That is, as theapplication amount of the upper layer resin 4 to the mold 5 increases(as the thickness of the upper layer resin 4 increases), thedistribution range of the CF3 bonds and the OCF2 bonds was found to bedeeper in the cured resin layer.

FIG. 23 is a graph showing the distribution states of OCF2 bonds in thecured resin layers of the optical films of Study Examples 1 to 4. Thehorizontal axis D (unit: nm) in FIG. 23 indicates the distance from thesurface having the uneven structure in the depth direction and is interms of polyhydroxy styrene equivalent. The vertical axis “M3D/M3S” inFIG. 23 indicates the ratio of M3D to M3S as defined below.

-   -   M3S: peak area of the OCF2 bonds in O1s peak detected on the        surface having the uneven structure    -   M3D: peak area of the OCF2 bonds in the O1s peak detected at a        position away from the surface having the uneven structure by D        (unit: nm) in the depth direction in terms of polyhydroxy        styrene equivalent

Here, the peak attributed to the OCF2 bonds was analyzed as a peakcorresponding to the peak separated from the O1s peak (e.g. peak O3 inFIG. 12).

As shown in FIG. 23, the amount of the OCF2 bonds was found to decreasein the depth direction of the cured resin layer. The decreasing tendencyof the amount of OCF2 bonds was found to be the slowest in Study Example4, followed by Study Example 3, Study Example 2, and Study Example 1 inthe given order. That is, as the application amount of the upper layerresin 4 to the mold 5 increases (as the thickness of the upper layerresin 4 increases), the distribution range of the OCF2 bonds was foundto be deeper in the cured resin layer.

As shown in FIGS. 21 to 23, the components (CF2 bonds, CF3 bonds, andOCF2 bonds) contained in the fluorine-containing monomer A and thefluorine-containing monomer B were contained at a high concentration ina region within 1 μm from the surface having the uneven structure in thedepth direction in terms of polyhydroxy styrene equivalent. Then, theconcentration levels of the fluorine-containing monomer A and thefluorine-containing monomer B were studied.

FIG. 24 is a graph showing the abundance ratio of carbon atoms of CF2bonds in the cured resin layers of the optical films of Study Examples 1to 4. The horizontal axis D (unit: nm) in FIG. 24 indicates the distancefrom the surface having the uneven structure in the depth direction andis in terms of polyhydroxy styrene equivalent. The vertical axis“M1ST/M1T” in FIG. 24 indicates the ratio of M1ST to M1T as definedbelow.

-   -   M1T: corresponding to the number of carbon atoms of the CF2        bonds in the cured resin layer    -   M1ST: corresponding to the number of carbon atoms of the CF2        bonds in the region within D (unit: nm) in terms of polyhydroxy        styrene equivalent from the surface having the uneven structure        in the depth direction

The ratio M1ST/M1T when the equation D=1000 nm (1 μm) held was 1 in allof Study Examples 1 to 4.

M1T and M1ST were calculated by the following procedures. In thefollowing, the calculation method in the case of Study Example 4 isshown. The same calculation was also performed for the other studyexamples.

First, the peak in the spectrum in the depth direction of the curedresin layer was separated into peaks attributed to the respectivebinding species, and the atomic concentration of each binding specieswas calculated. FIG. 25 is a graph showing the proportions of thenumbers of the atoms of the respective binding species relative to thetotal number of carbon atoms, nitrogen atoms, oxygen atoms, and fluorineatoms in the cured resin layer of the optical film of Study Example 4.FIG. 25 selectively shows the peak C6 (CF2 bonds), the peak C7 (CF3bonds and OCF2 bonds), and the peak O3 (OCF2 bonds).

The horizontal axis D (unit: nm) in FIG. 25 indicates the distance fromthe surface having the uneven structure in the depth direction and is interms of polyhydroxy styrene equivalent. The vertical axis “atomicconcentration” in FIG. 25 indicates the proportion of the number ofatoms of respective binding species (unit: atom %) relative to the totalnumber of carbon atoms, nitrogen atoms, oxygen atoms, and fluorineatoms. Specifically, the proportions are as described below.

-   -   C1s (C6): the proportion of the number of carbon atoms of the        CF2 bonds relative to the total number of carbon atoms, nitrogen        atoms, oxygen atoms, and fluorine atoms    -   C1s (C7): the proportion of the number of carbon atoms of the        CF3 bonds and OCF2 bonds relative to the total number of carbon        atoms, nitrogen atoms, oxygen atoms, and fluorine atoms    -   O1 s (O3): the proportion of the number of oxygen atoms of the        OCF2 bonds relative to the total number of carbon atoms,        nitrogen atoms, oxygen atoms, and fluorine atoms

Next, based on the results shown in FIG. 25, the M1T and M1ST werecalculated from the areas of the profiles as shown in FIG. 26. FIG. 26is a graph showing M1T and M1ST in Study Example 4 shown in FIG. 24.

-   -   M1T: area of profile of C1s (C6)    -   M1ST: area in the range of horizontal axis 0 to D in profile of        C1s (C6)

FIG. 27 is a graph showing the abundance ratio of carbon atoms of CF3bonds and OCF2 bonds in the cured resin layers of the optical films ofStudy Examples 1 to 4. The horizontal axis D (unit: nm) in FIG. 27indicates the distance from the surface having the uneven structure inthe depth direction and is in terms of polyhydroxy styrene equivalent.The vertical axis “M2ST/M2T” in FIG. 27 indicates the ratio of M2ST toM2T as defined below.

-   -   M2T: corresponding to the number of carbon atoms of the CF3        bonds and the OCF2 bonds in the cured resin layer    -   M2ST: corresponding to the number of carbon atoms of the CF3        bonds and the OCF2 bonds in the region within D (unit: nm) in        terms of polyhydroxy styrene equivalent from the surface having        the uneven structure in the depth direction

The ratio M2ST/M2T when the equation D=1000 nm (1 μm) held was 1 in allof Study Examples 1 to 4.

M2T and M2ST were calculated by the following procedures. In thefollowing, the calculation method in the case of Study Example 4 isshown. The same calculation was also performed for the other studyexamples.

Based on the results shown in FIG. 25, the M2T and M2ST were calculatedfrom the areas of the profiles as shown in FIG. 28. FIG. 28 is a graphshowing M2T and M2ST in Study Example 4 shown in FIG. 27.

-   -   M2T: area of profile of C1s (C7)    -   M2ST: area in the range of horizontal axis 0 to D in profile of        C1s (C7)

FIG. 29 is a graph showing the abundance ratio of oxygen atoms of OCF2bonds in the cured resin layers of the optical films of Study Examples 1to 4. The horizontal axis D (unit: nm) in FIG. 29 indicates the distancefrom the surface having the uneven structure in the depth direction andis in terms of polyhydroxy styrene equivalent. The vertical axis“M3ST/M3T” in FIG. 29 indicates the ratio of M3ST to M3T as definedbelow.

-   -   M3T: corresponding to the number of oxygen atoms of the OCF2        bonds in the cured resin layer    -   M3ST: corresponding to the number of oxygen atoms of the OCF2        bonds in the region within D (unit: nm) in terms of polyhydroxy        styrene equivalent from the surface having the uneven structure        in the depth direction

The ratio M3ST/M3T when the equation D=1000 nm (1 μm) held was 1 inStudy Examples 1 to 3, and 0.99 in Study Example 4.

M3T and M3ST were calculated by the following procedures. In thefollowing, the calculation method in the case of Study Example 4 isshown. The same calculation was also performed for the other studyexamples.

Based on the results shown in FIG. 25, the M3T and M3ST were calculatedfrom the areas of the profiles as shown in FIG. 30. FIG. 30 is a graphshowing M3T and M3ST in Study Example 4 in FIG. 29.

-   -   M3T: area of profile of O1s (O3)    -   M3ST: area in the range of horizontal axis 0 to D in profile of        O1s (O3)

As shown in FIG. 24, FIG. 27, and FIG. 29, when the equation D=1000 nm(1 μm) held, all the ratios M1ST/M1T, M2ST/M2T, and M3ST/M3T in eachstudy example were 0.99 or more. That is, 99% or more of the number ofatoms in the cured resin layer about the carbon atoms of the CF2 bonds,the carbon atoms of the CF3 bonds and OCF2 bonds, and the oxygen atomsof the OCF2 bonds was contained in a region within 1 μm in terms ofpolyhydroxy styrene equivalent from the surface having the unevenstructure in the depth direction. From the viewpoint of achieving a highconcentration of the components contained in the fluorine-containingmonomer A and the fluorine-containing monomer B on the surface side ofthe cured resin layer (surface side of the uneven structure) andsufficiently improving the anti-fouling properties, preferably 95% ormore, more preferably 99% or more, of the number of atoms in the curedresin layer about at least one kind of atom selected from the groupconsisting of the carbon atoms of the CF2 bonds, the carbon atoms of theCF3 bonds and the OCF2 bonds, and the oxygen atoms of the OCF2 bonds iscontained in the region within 1 μm in terms of polyhydroxy styreneequivalent from the surface having the uneven structure in the depthdirection. Also, still more preferably, 99% or more of the number ofatoms in the cured resin layer about the carbon atoms of the CF2 bonds,the carbon atoms of the CF3 bonds and the OCF2 bonds, and the oxygenatoms of the OCF2 bonds is contained in the region within 1 μm in termsof polyhydroxy styrene equivalent from the surface having the unevenstructure in the depth direction.

As described above, in consideration of the results shown in Evaluation4, the components contained in the fluorine-containing monomer A and thefluorine-containing monomer B were found to be contained at a highconcentration on the surface side of the cured resin layer (surface sideof the uneven structure) even when the concentration of fluorine atomsin the cured resin layer was as low as 2% or lower. Such a state enablesproduction of an optical film having sufficiently excellent anti-foulingproperties.

[Additional Remarks]

One aspect of the present invention may be a method for producing anoptical film having on a surface thereof an uneven structure providedwith projections at a pitch equal to or shorter than the wavelength ofvisible light, the method including the steps of: (1) applying a lowerlayer resin and an upper layer resin; (2) forming a resin layer havingthe uneven structure on a surface thereof by pressing a mold against thelower layer resin and the upper layer resin from the upper layer resinside in the state where the applied lower layer resin and upper layerresin are stacked; and (3) curing the resin layer, the lower layer resincontaining at least one kind of first monomer that contains no fluorineatoms, the upper layer resin containing a fluorine-containing monomerand at least one kind of second monomer that contains no fluorine atoms,at least one of the first monomer and the second monomer containing acompatible monomer that is compatible with the fluorine-containingmonomer and being dissolved in the lower layer resin and the upper layerresin.

The phrase “applying a lower layer resin and an upper layer resin” inthe above-described step (1) encompasses not only the case of applyingin layers the lower layer resin and the upper layer resin to the samebase material but also the case of applying the lower layer resin andthe upper layer resin to different base materials. The case of applyingthe lower layer resin and the upper layer resin to different basematerials may be, for example, the case of applying the lower layerresin to a base film and the upper layer resin to the mold.

The phrase “pressing a mold against the lower layer resin and the upperlayer resin from the upper layer resin side in the state where theapplied lower layer resin and upper layer resin are stacked” in theabove-described step (2) encompasses not only the case of pressing themold after the lower layer resin and the upper layer resin are stackedbut also the case of pressing the mold while stacking the lower layerresin and the upper layer resin. In other words, the phrase encompassesa method of, in the above-described step (2), stacking the lower layerresin and the upper layer resin (hereinafter, also referred to as astacking step) and pressing the mold against the lower layer resin andthe upper layer resin from the upper layer resin side (hereinafter, alsoreferred to as a pressing step) at the same timing or different timings.

The method for performing the stacking step and the pressing step atdifferent timings is preferably performed by any of the followingmethods (i) to (iv).

(i) A method of sequentially applying the lower layer resin and theupper layer resin to a base film (stacking step) and then pressing themold against the lower layer resin and the upper layer resin from theupper layer resin side (pressing step).

That is, the step (1) may be performed by sequentially applying thelower layer resin and the upper layer resin to a base film. In thiscase, use of an apparatus employing a common application method (e.g.gravure method, slot die method) in combination enables suitableapplication of the lower layer resin and the upper layer resin.

(ii) A method of simultaneously applying the lower layer resin and theupper layer resin to a base film (the upper layer resin is formed on thelower layer resin on the side opposite to the base film) (the stackingstep) and then pressing the mold against the lower layer resin and theupper layer resin from the upper layer resin side (the pressing step).

That is, the step (1) may be performed by simultaneously applying thelower layer resin and the upper layer resin to a base film. In thiscase, the lower layer resin and the upper layer resin can be suitablyapplied. Furthermore, the application device can be a simple one and thenumber of steps can be decreased, compared with the case of sequentiallyapplying the lower layer resin and the upper layer resin to the basefilm, so that the productivity is improved.

(iii) A method of sequentially applying the upper layer resin and thelower layer resin to the mold (the stacking step) and then pressing themold to which the upper layer resin and the lower layer resin have beenapplied against a base film (the pressing step).

That is, the step (1) may be performed by sequentially applying theupper layer resin and the lower layer resin to the mold. In this case,for example, use of a flexible material for the mold facilitatesformation of the uneven structure regardless of the shape of the basefilm.

(iv) A method of simultaneously applying the upper layer resin and thelower layer resin to the mold (the lower layer resin is formed on theupper layer resin on the side opposite to the mold) (the stacking step),and then pressing the mold to which the upper layer resin and the lowerlayer resin have been applied against a base film (the pressing step).

That is, the step (1) may be performed by simultaneously applying theupper layer resin and the lower layer resin to the mold. In this case,use of a flexible material for the mold facilitates formation of theuneven structure regardless of the shape of the base film.

The method of performing the stacking step and the pressing step at thesame timing is preferably the following method (v).

(v) A method of applying the lower layer resin to a base film, applyingthe upper layer resin to the mold, and stacking the upper layer resin onthe lower layer resin (the stacking step) while pressing, from the upperlayer resin side, the mold to which the upper layer resin has beenapplied against the lower layer resin applied to the base film (thepressing step).

That is, the step (1) may be performed by applying the lower layer resinto a base film and the upper layer resin to the mold, and the step (2)may be performed by pressing, from the upper layer resin side, the moldto which the upper layer resin has been applied against the lower layerresin applied to the base film. In this case, stacking of the upperlayer resin on the lower layer resin and formation of the unevenstructure can be simultaneously performed. Furthermore, the number ofsteps can be reduced compared with the case of sequentially applying thelower layer resin and the upper layer resin to the base film. Also, thepresent method can suitably improve the anti-fouling properties, and inparticular, can minimize the loss of the constituent materials of theupper layer resin.

Hereinafter, preferred characteristics of the method for producing anoptical film according to the present invention are described. Theseexamples may be appropriately combined within the spirit of the presentinvention.

The upper layer resin may be applied by a spray method. Thereby, thethickness of the upper layer resin can be easily adjusted, and inparticular, the upper layer resin can be applied to a uniform thicknesseven when the upper layer resin is reduced in thickness in order tosuitably increase the concentration of fluorine atoms in the vicinity ofthe surface of the upper layer resin. In the case of thinly applying theupper layer resin, the resin is preferably applied using, for example, aswirl nozzle, an electrostatic nozzle, or an ultrasonic nozzle. Sincethe fluorine-containing monomer contained in the upper layer resin isrelatively expensive, thinly applying the upper layer resin enablesreduction of the material cost of the optical film. Also, use of thespray method enables reduction of the apparatus cost.

The mold may have been subjected to a release treatment. Thereby, thesurface free energy of the mold can be lowered, and thefluorine-containing monomer can be suitably concentrated in the vicinityof the surface of the resin layer (the upper layer resin) when the moldis pressed. The release treatment also suitably prevents thefluorine-containing monomer from moving away from the vicinity of thesurface of the resin layer before the resin layer is cured. As a result,the concentration of the fluorine atoms in the vicinity of the surfaceof the optical film can be suitably increased.

The release treatment may be a surface treatment with a silane couplingagent. Thereby, the release treatment can be performed suitably.

The lower layer resin may have a viscosity of higher than 10 cp andlower than 10000 cp at 25° C. Thereby, the fluorine-containing monomercontained in the upper layer resin can be prevented from being mixedinto the lower layer resin in the state where the upper layer resin andthe lower layer resin are stacked, so that the concentration of fluorineatoms in the vicinity of the surface of the upper layer resin can besuitably prevented from decreasing. Also, the applicability of the lowerlayer resin can be suitably improved.

The upper layer resin may have a viscosity of higher than 0.1 cp andlower than 100 cp at 25° C. Thereby, suitable fluidity of thefluorine-containing monomer contained in the upper layer resin can beachieved. Furthermore, the applicability of the upper layer resin can besuitably improved.

The fluorine-containing monomer may be curable by ultraviolet rays.Thereby, the fluorine-containing monomer can be used effectively.

The upper layer resin may have a concentration of thefluorine-containing monomer of higher than 0% by weight and lower than20% by weight. Thereby, occurrence of cloudiness due to a large amountof the fluorine-containing monomer can be suitably prevented.

The upper layer resin may contain no solvent. That is, the upper layerresin may be a non-solvent resin. In the case that a solvent is notadded to the upper layer resin, an apparatus for drying and removing thesolvent is not necessary, and thus the apparatus cost can be suppressed.Also, since no solvent is used, the cost for the solvent can beeliminated and the productivity can be improved. In contrast, if asolvent is added to the upper layer resin, the fluorine-containingmonomer may be mixed too well, which may decrease the concentration ofthe fluorine atoms in the vicinity of the surface of the optical film.Also, the volatility of the upper layer resin will be high, which maydecrease the applicability.

The compatible monomer may include an acid amide bond in the molecule.Thereby, the compatible monomers can be used effectively.

A difference between the solubility parameter of the compatible monomerand the solubility parameter of the fluorine-containing monomer may bein the range of 0 (cal/cm3)1/2 to 4.0 (cal/cm3)1/2. Thereby, thecompatibility between the compatible monomer and the fluorine-containingmonomer can be sufficiently improved.

A difference between the solubility parameter of the compatible monomerand the solubility parameter of a monomer component other than thecompatible monomer in the lower layer resin may be in the range of 0(cal/cm3)1/2 to 3.0 (cal/cm3)1/2. Thereby, the compatibility between thecompatible monomer and the lower layer resin can be sufficientlyimproved.

A difference between the solubility parameter of the compatible monomerand the solubility parameter of a monomer component other than thecompatible monomer in the upper layer resin may be in the range of 0(cal/cm3)1/2 to 3.0 (cal/cm3)1/2. Thereby, the compatibility between thecompatible monomer and the upper layer resin can be sufficientlyimproved.

A difference between the solubility parameter of the fluorine-containingmonomer and the solubility parameter of a monomer component other thanthe compatible monomer in the lower layer resin may be in the range of3.0 (cal/cm3)1/2 to 5.0 (cal/cm3)1/2. Thereby, the fluorine-containingmonomer contained in the upper layer resin can be prevented from beingmixed into the lower layer resin in the state where the lower layerresin and the upper layer resin are stacked, so that the concentrationof fluorine atoms in the vicinity of the surface of the upper layerresin can be suitably prevented from decreasing.

A difference between the solubility parameter of the base film and thesolubility parameter of a monomer component other than the compatiblemonomer in the lower layer resin may be in the range of 0 (cal/cm3)1/2to 5.0 (cal/cm3)1/2. Thereby, the adhesion between the base film and thelower layer resin can be sufficiently improved.

Hereinafter, examples of preferred characteristics of the optical filmof the present invention are described. The examples may beappropriately combined within the spirit of the present invention.

A surface of the optical film may have a contact angle with water of100° or greater and a contact angle with hexadecane of 40° or greater.Thereby, an optical film having sufficiently high water repellency andoil repellency can be obtained.

The proportion of the number of the fluorine atoms relative to the totalnumber of the carbon atoms, the nitrogen atoms, the oxygen atoms, andthe fluorine atoms on the surface having the uneven structure may be 43atom % or higher. Thereby, an optical film having sufficiently excellentanti-fouling properties can be obtained.

The cured resin layer may have a concentration of the fluorine atoms of2% or lower, and in the measurement by X-ray photoelectron spectroscopyunder the conditions of an X-ray beam diameter of 100 μm, an analysisarea of 1000 μm×500 μm, and a photoelectron extraction angle of 45°, 95%or more of the number of atoms in the cured resin layer about at leastone kind of atom selected from the group consisting of the carbon atomsof CF2 bonds, the carbon atoms of CF3 bonds and OCF2 bonds, and theoxygen atoms of the OCF2 bonds may be contained in a region within 1 μmin terms of polyhydroxy styrene equivalent from the surface having theuneven structure in the depth direction. Thereby, the binding speciesincluding fluorine atoms are contained at a high concentration on thesurface side of the cured resin layer (surface side of the unevenstructure) even when the concentration of fluorine atoms in the curedresin layer is as low as 2% or lower, so that an optical film havingsufficiently excellent anti-fouling properties can be obtained.

REFERENCE SIGNS LIST

-   1, 101 a, 101 b: optical film-   2, 102: base film-   3, 103 a, 103 b: lower layer resin-   4, 104: upper layer resin-   5, 105: mold-   6, 106 a, 106 b: projection-   7, 107: fluorine atom-   8: resin layer-   109: silicon dioxide layer-   P, Q1, Q2: pitch-   D_(L): thickness of lower layer resin-   D_(U): thickness of upper layer resin-   C1, C2, C3, C4, C5, C6, C7, C_(R), O1, O2, O3, O_(R): peak

1. An optical film comprising a cured resin layer having an unevenstructure on a surface thereof, the uneven structure being provided withprojections at a pitch equal to or shorter than the wavelength ofvisible light, the cured resin layer containing carbon atoms, nitrogenatoms, oxygen atoms, and fluorine atoms as constituent atoms, the ratioof a peak area of OCF2 bonds to the sum of a peak area of C—O bonds anda peak area of C═O bonds being 0.3 or higher according to spectraobtained by curve-fitting for the O1s peak on the surface having theuneven structure with a peak attributed to the C—O bonds, a peakattributed to the C═O bonds, and a peak attributed to the OCF₂ bonds,the O1s peak being measured by X-ray photoelectron spectroscopy underthe conditions of an X-ray beam diameter of 100 μm, an analysis area of1000 μm×500 μm, and a photoelectron extraction angle of 45°.
 2. Theoptical film according to claim 1, wherein the ratio of the peak area ofthe OCF₂ bonds to the sum of the peak area of the C—O bonds and the peakarea of the C═O bonds is 0.6 or higher.
 3. The optical film according toclaim 2, wherein the ratio of the peak area of the OCF₂ bonds to the sumof the peak area of the C—O bonds and the peak area of the C═O bonds is1 or higher.
 4. The optical film according to claim 1, wherein the ratioof the peak area of the OCF₂ bonds to the sum of the peak area of theC—O bonds and the peak area of the C═O bonds is 1.1 or lower.
 5. Theoptical film according to claim 1, D satisfying the equationMF_(D)/MF_(S)=0.3 is 240 nm or more, where MF_(S), expressed with theunit of atom %, is the proportion of the number of the fluorine atomsrelative to the total number of the carbon atoms, the nitrogen atoms,the oxygen atoms, and the fluorine atoms on the surface having theuneven structure, and MF_(D), expressed with the unit of atom %, is theproportion of the number of the fluorine atoms relative to the totalnumber of the carbon atoms, the nitrogen atoms, the oxygen atoms, andthe fluorine atoms at a position away from the surface having the unevenstructure by D, expressed with the unit of nm, in the depth direction interms of polyhydroxy styrene equivalent, the number of the atoms beingmeasured by X-ray photoelectron spectroscopy under the conditions of anX-ray beam diameter of 100 μm, an analysis area of 1000 μm×500 μm, and aphotoelectron extraction angle of 45°.
 6. The optical film according toclaim 5, wherein D satisfying the equation MF_(D)/MF_(S)=0.3 is 275 nmor more.
 7. The optical film according to claim 5, wherein D satisfyingthe equation MF_(D)/MF_(S)=0.3 is 350 nm or lower.
 8. The optical filmaccording to claim 5, wherein D satisfying the equation MF_(D)/MF_(S)=0is 1220 nm or more.
 9. The optical film according to claim 8, wherein Dsatisfying the equation MF_(D)/MF_(S)=0 is 1380 nm or more.
 10. Theoptical film according to claim 9, wherein D satisfying the equationMF_(D)/MF_(S)=0 is 1540 nm or more.
 11. The optical film according toclaim 1, wherein the cured resin layer has a concentration of thefluorine atoms of 2% or lower, and in the measurement by X-rayphotoelectron spectroscopy under the conditions of an X-ray beamdiameter of 100 μm, an analysis area of 1000 μm×500 μm, and aphotoelectron extraction angle of 45°, 95% or more of the number ofatoms in the cured resin layer about at least one kind of atom selectedfrom the group consisting of the carbon atoms of CF2 bonds, the carbonatoms of CF3 bonds and the OCF₂ bonds, and the oxygen atoms of the OCF₂bonds is contained in a region within 1 μm in terms of polyhydroxystyrene equivalent from the surface having the uneven structure in thedepth direction.
 12. The optical film according to claim 11, wherein 99%or more of the number of atoms in the cured resin layer about at leastone kind of atom selected from the group consisting of the carbon atomsof the CF2 bonds, the carbon atoms of the CF3 bonds and the OCF₂ bonds,and the oxygen atoms of the OCF₂ bonds is contained in a region within 1μm in terms of polyhydroxy styrene equivalent from the surface havingthe uneven structure in the depth direction.
 13. The optical filmaccording to claim 1, wherein a surface of the optical film has acontact angle with water of 100° or greater and a contact angle withhexadecane of 40° or greater.
 14. The optical film according to claim13, wherein the surface of the optical film has a contact angle withwater of 150° or greater and a contact angle with hexadecane of 90° orgreater.
 15. The optical film according to claim 1, wherein the pitch isin the range of 100 nm to 400 nm.